Role of culture for mycobacteria in fine-needle aspiration diagnosis of tuberculous lymphadenitis

A total of 390 cases of tuberculous lymphadenitis was subjected to fine-needle aspiration cytology; 100 of the aspirates were subjected to culture for mycobacteria. The overall acid-fast bacilli (AFB) positivity in smears was 23.58%, with a maximum positivity of 32.94% in smears with both necrosis and granuloma. The overall rate of isolation of mycobacteria on culture was 35%. Mycobacteria were more frequently isolated from caseating lesions (40%) than noncaseating lesions (9%). Caseating lesions with granuloma had the highest AFB (smear and/or culture) positivity at 52%. Mycobacterium avium infection was diagnosed by culture in one case.     

Detection and identification of mycobacteria by amplification of RNA and DNA in pretreated blood and bone marrow aspirates by a simple lysis method.

A sodium dodecyl (lauryl) sulfate method was evaluated for the preparation of blood specimens and bone marrow aspirates for use in two amplification procedures (Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test [AMTDT] and Roche Amplicor M. avium/M. intracellulare [MAI] Test) for the detection and identification of Mycobacterium tuberculosis and M. avium and M. intracellulare, respectively. The AMTDT is based on amplification of rRNA, whereas the Amplicor MAI Test amplifies a specific DNA region of the 16S rRNA gene. The results of amplification techniques were compared with those of standard culture and culture in BACTEC 13A and BACTEC 12B liquid media. A total of 121 blood specimens and 15 bone marrow aspirates were collected from 136 AIDS patients. Mycobacterial growth was recovered for 103 specimens; 35 yielded M. tuberculosis, 62 yielded M. avium, 5 yielded M. genavense, and 1 yielded M. kansasii. The values of sensitivity and specificity in pretreated specimens for detection of M. tuberculosis by the AMTDT were 94.3 and 100%, respectively, and those for detection of M. avium by the Amplicor MAI Test were 91.9 and 100%, respectively. The simple lysis method described in the present work allows the recovery of mycobacteria from blood specimens and bone marrow aspirates and may be used in combination with the AMTDT and the Amplicor MAI Test to detect and identify different members of the genus Mycobacterium. This method might also be applicable for the identification of mycobacteria from blood culture fluids with acridinium-ester-labeled DNA probes.     

Cytomorphological patterns of M. bovis BCG and M. tuberculosis on fine needle aspiration biopsies: Does HIV make a difference?

To determine if fine needle aspiration (FNAB) of mycobacterial lymphadenopathy can differentiate infection with M. bovis BCG (BCG) from M. tuberculosis (TB) and whether HIV status affects discriminatory cytological features. A retrospective study of culture positive, fine needle aspiration biopsies of lymph nodes in children (<13 years) between 2003 and 2008. A total of 77 aspirates were available for evaluation with 67 (87%) patients having known HIV status. BCG occurred at a younger age (6 months), predominantly axillary lymph nodes (90%) compared with TB (5 years and 20% axillary lymph nodes). Amorphous necrosis was only seen in aspirates from TB lymph nodes, while in HIV negative children with TB, foamy macrophages were absent. On ZN staining there were more organisms in the BCG group and in HIV positive patients the organisms were present in both extra- and intracellular locations, whereas in the HIV negative patients the organisms were predominantly extracellular in location. Demographic and cytomorphologic features that can assist in distinguishing between the two mycobacterial species include: age of patient, location of the lymph node, and presence/absence of amorphous necrosis and foamy macrophages on FNAB. However the only reliable method to identify the mycobacterial species is by mycobacterial culture and/or PCR.     

Macroscopic purulence, leukocyte counts, and bacterial morphotypes in relation to culture findings for sinus secretions in acute maxillary sinusitis

Macroscopic purulence, leukocyte counts, and bacterial morphotypes in Gram-stained smears were investigated in 335 sinus secretions (240 aspirates and 95 injection aspirates) obtained by puncture in 234 young patients with acute maxillary sinusitis. Over 90% of the 147 aspirates macroscopically classified as purulent also contained high numbers of leukocytes (greater than 20 per oil immersion field). A total of 82% of the 147 macroscopically purulent aspirates and 79% of the 156 aspirates containing high numbers of leukocytes yielded presumed sinus pathogens by culture in quantities of greater than 10(3) CFU/ml. Streptococcus pneumoniae or Streptococcus pyogenes was associated relatively more often (92 or 87%, respectively) with high numbers of leukocytes than Haemophilus influenzae, which was not infrequently (29%) recovered from the less purulent aspirates. When a bacterial morphotype was seen in the Gram-stained smear, a corresponding sinus pathogen was isolated in quantities of greater than 10(3) CFU/ml in 92% of aspirates. Other bacterial species (most often staphylococci) were usually isolated in low numbers and were almost never seen in the smear, suggesting nasal contamination. The 95 injection aspirates behaved, to a large extent, like diluted aspirates, with the exception that there was a higher frequency of probable nasal contamination. Macroscopic purulence, high leukocyte counts, and bacterial morphotypes seen in Gram-stained smears each predicted well the isolation of a presumed sinus pathogen and in some cases supported the significance of an otherwise doubtful culture finding. However, the macroscopic appearance of the secretion should not be used to screen samples for culture, because in several cases H. influenzae grew from nonpurulent samples as well.     

Evaluation of the Speed-oligo Direct Mycobacterium tuberculosis Assay for Molecular Detection of Mycobacteria in Clinical Respiratory Specimens

We present the first evaluation of a novel molecular assay, the Speed-oligo Direct Mycobacterium tuberculosis (SO-DMT) assay, which is based on PCR combined with a dipstick for the detection of mycobacteria and the specific identification of M. tuberculosis complex (MTC) in respiratory specimens. A blind evaluation was carried out in two stages: first, under experimental conditions on convenience samples comprising 20 negative specimens, 44 smear- and culture-positive respiratory specimens, and 11 sputa inoculated with various mycobacterium-related organisms; and second, in the routine workflow of 566 fresh respiratory specimens (4.9% acid-fast bacillus [AFB] smear positives, 7.6% MTC positives, and 1.8% nontuberculous mycobacteria [NTM] culture positives) from two Mycobacterium laboratories. SO-DMT assay showed no reactivity in any of the mycobacterium-free specimens or in those with mycobacterium-related organisms. Compared to culture, the sensitivity in the selected smear-positive specimens was 0.91 (0.92 for MTC and 0.90 for NTM), and there was no molecular detection of NTM in a tuberculosis case or vice versa. With respect to culture and clinical data, the sensitivity, specificity, and positive and negative predictive values for the SO-DMT system in routine specimens were 0.76 (0.93 in smear positives [1.0 for MTC and 0.5 for NTM] and 0.56 in smear negatives [0.68 for MTC and 0.16 for NTM]), 0.99, 0.85 (1.00 in smear positives and 0.68 in smear negatives), and 0.97, respectively. Molecular misidentification of NTM cases occurred when testing 2 gastric aspirates from two children with clinically but not microbiologically confirmed lung tuberculosis. The SO-DMT assay appears to be a fast and easy alternative for detecting mycobacteria and differentiating MTC from NTM in smear-positive respiratory specimens.     

Comparison of a Nonradiometric System with Bactec 12B and Culture on Egg-Based Media for Recovery of Mycobacteria from Clinical Specimens

The MB/BacT (Organon-Teknika, USA) is a fully automated, rapid, nonradiometric system for the culture of mycobacteria from clinical samples. The rate of recovery of mycobacteria and the time to detection obtained with the MB/BacT were compared with those obtained with Löwenstein-Jensen and Coletsos solid media and Bactec 7H12 (12B) (Becton-Dickinson, USA) broth when 600 processed specimens were inoculated into all media in parallel. Specimens included 383 respiratory samples, 20 urine samples, 23 purulent exudates, 13 stool samples, 103 blood samples, 14 bone marrow aspirates, and 44 body fluid samples or aspirates. Overall, 106 mycobacterial isolates comprising six species were recovered, of which 100 (94.3%) were detected with MB/BacT, 98 (92.5%) with egg-based media, and 96 (90.2%) with Bactec 12B. The recovery rates of Mycobacterium tuberculosis complex with MB/BacT, egg-based media, and Bactec 12B were 98.7%, 93.7, and 89.9%, respectively. The average number of days to detection of single mycobacterial isolates was 14.2 days for MB/BacT, 26.1 days for egg-based media, and 11.7 days for Bactec 12B. The contamination rates were higher in MB/BacT (5%) than in Bactec 12B (1.8%) or egg-based media (1.5%). MB/BacT is a reliable, nonradiometric, less labor-intensive alternative to Bactec 12B for recovery of mycobacteria, but, as with other liquid culture methods, MB/BacT should be used in combination with a solid medium, not on its own.     

Cystic change in metastatic lymph nodes: a common diagnostic pitfall in fine-needle aspiration cytology

Fine-needle aspiration cytology (FNAC) of cystic metastases is a challenging diagnostic category and has been investigated in a limited number of malignancies and sites. The present study retrospectively reviewed 1,211 FNAC of superficial masses, including lymph nodes (1,102 aspirates), benign cystic lesions (64 aspirates), and lymphocysts (45 aspirates) with the aim of determining the tumors that cause cystic change in metastases. Cytology results from 1,102 lymph node aspirations were suspicious or positive for malignancy in 541 specimens (49.1%), benign in 230 (20.9%), and unsatisfactory in 331 (30%). There were 28 malignant aspirates demonstrating cystic change (5.2%). The tumor type that most frequently caused cystic change was thyroid papillary carcinoma (42.8% of cases), followed by squamous cell carcinoma (primary in the head and neck region 30.8% and in the skin 24%), tumors of unknown origin (6.3%), serous papillary carcinoma of the ovary or endometrium (4.8%), and malignant melanoma (2.1%). Cystic change was observed most commonly in the head and neck region lymph nodes (60%). The most challenging lesions to assess using FNAC were metastatic lymph nodes showing cystic change, accounting for six of the 16 false-negative diagnoses and one false-positive diagnosis. The results of this study suggest that cystic change in metastatic lymph nodes occurs in certain types of tumors and is an important cause of diagnostic error. FNAC should be repeated in case of suspicious hypocellular cystic aspirations, especially in patients with known malignancy.     

Acridine orange staining of smears for demonstration ofMycobacterium tuberculosis

Acridine orange staining for the detection of mycobacteria was compared with staining by auramine 0 and with mycobacterial culture in a series of 1071 clinical specimens. A total of 78 (7 %) specimens were positive by staining. No false positive or negative findings were recorded by the acridine orange method. The two fluorochromes proved equal in their ability to detect mycobacteria in specimens from culture positive cases of tuberculosis. In the rapid bacteriological diagnosis of tuberculosis, acridine orange offers a good alternative to auramine 0 which is considered carcinogenic.     

Mycobacterial culture of fine needle aspirate - a useful tool in diagnosing tuberculous lymphadenitis

A prospective study was undertaken on suspected lymph node TB (LNTB) patients, to evaluate the diagnostic utility of mycobacterial culture of fine needle aspirate (FNA), in comparison with the cytological examination and acid fast staining. Eighty percent of 157 aspirates studied were positive by cytological examination; 18% by ZN smear and 45% were positive by culture. Twelve aspirates which were negative by cytological features yielded positive mycobacterial cultures; four out of these were from HIV positive patients. Our observations suggest that supplementing FNA cytology with mycobacterial culture would increase the sensitivity of diagnosing LNTB; in addition to giving a highly specific diagnosis.     

Performance of a commercial nucleic acid amplification test with extrapulmonary specimens for the diagnosis of tuberculosis

The laboratory diagnosis of tuberculosis (TB) on extrapulmonary specimens is particularly challenging. A number of commercial nucleic acid amplification tests able to detect and identify Mycobacterium tuberculosis (MTB) complex directly from respiratory secretions have been developed, but their use on extrapulmonary samples still calls for validation. The BDProbeTec ET Mycobacterium tuberculosis Complex Direct Detection Assay (DTB) was applied to 918 consecutive extrapulmonary specimens (collected from 863 patients), including 84 gastric aspirates, 145 urine, 136 sterile body fluids, 83 cerebrospinal (CSF) fluids, 237 fine-needle aspirates, 175 pus, 56 biopsies, and two stool specimens. The results were compared with those of acid-fast staining and culture (solid plus liquid media), setting the combination of culture and clinical diagnosis as the gold standard. Ninety-two specimens yielded culture positive for MTB and 24 (smear- and culture-negative) were from patients with TB clinical diagnosis. Of these, 96 were DTB-positive, including all of those from culture-negative TB cases. From 26 specimens, nontuberculous mycobacteria were grown. Two of these specimens were positive by the DTB assay. Finally, of the 776 samples that were smear- and culture-negative for acid-fast bacilli (AFB), collected from patients for whom the diagnosis of TB was excluded, six were DTB-positive. The overall sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) of extrapulmonary samples were 82.7, 99.0, 92.3, and 97.8%, respectively. Although, at present, amplification assays cannot replace culture techniques, DTB proved to be rapid and specific for the detection of MTB in extrapulmonary samples.     

Improved Decontamination Method for Recovering Mycobacteria from Patients with Cystic Fibrosis

In order to improve the recovery of mycobacteria from patients with cystic fibrosis, the present study evaluated a two-step decontamination procedure for clinical specimens. A total of 920 specimens obtained from 239 patients with cystic fibrosis were treated initially with N-acetyl-L-cysteine/sodium hydroxide. Of these specimens, 31 (3.3%) showed mycobacterial growth and 415 (45.1%) remained contaminated. Contaminated specimens were then subjected to a second round of decontamination, using a combination of N-acetyl-L-cysteine/sodium hydroxide and oxalic acid. Following this second decontamination, the number of specimens overgrown by microorganisms other than mycobacteria was reduced to 7.3%, and an additional 10 specimens positive for mycobacteria were found. The results suggest this two-step protocol could improve the recovery of mycobacteria from heavily contaminated specimens. Electronic Publication     

Evaluation of PCR for diagnosis of visceral leishmaniasis.

An evaluation of Leishmania PCR was performed with bone marrow, lymph node, and blood samples from 492 patients, 60 positive controls, and 90 negative controls. Results were compared with microscopy results for Giemsa-stained smears. PCR and microscopy of lymph node and bone marrow aspirates from patients with microscopically confirmed visceral leishmaniasis (VL) were equally sensitive. However, in patients clinically suspected of having VL and in whom parasites could not be demonstrated by microscopy, PCR was positive for 12 of 23 (52.2%) lymph node aspirates and 8 of 12 (66.7%) bone marrow aspirates, thus confirming the clinical diagnosis of VL. With PCR on filter paper, Leishmania DNA was detected in the blood of 33 of 47 (70%) patients with confirmed VL and in 2 of 11 (19%) patients suspected of having VL. Positive PCR results were more frequently found for blood samples on filter paper than for samples stored in EDTA. In conclusion, PCR is a more sensitive method than microscopy for the detection of Leishmania in lymph node and bone marrow aspirates, being especially useful for the confirmation of cases of suspected VL. Blood from a finger prick may be used for the initial PCR screening of people suspected of having VL. If the PCR of blood is negative, one should perform PCR with lymph node and/or bone marrow material, because PCR with these materials is more often positive.     

Use of PCR for Diagnosis of Post-Kala-Azar Dermal Leishmaniasis

Microscopy and PCR were compared for use in the diagnosis of post-kala-azar dermal leishmaniasis (PKDL) in 63 patients. Aspirates of lymph nodes (samples from 52 patients), skin (23 samples), and bone marrow (18 samples) were used. For 11 patients lymph node aspiration could be repeated 6 months after they recovered from PKDL. During active PKDL, PCR was positive for 42 of 52 (80.8%) lymph node aspirates and 19 of 23 (82.7%) skin aspirates, whereas microscopy was positive for only 9 of 52 (17.3%) lymph node aspirates and 7 of 23 (30.4%) skin aspirates. PCR was always positive when parasites were seen by microscopy. When the results obtained with lymph node and skin aspirates from the same patient (n = 16) were compared, there was complete agreement. Bone marrow samples were negative by microscopy and PCR for 16 patients and positive by both methods for 1 patient; for one sample only the PCR was positive. PCR confirmed the co-occurrence of visceral leishmaniasis and PKDL in one patient and confirmed the suspicion of this co-occurrence in the other patient. After recovery, no parasites were found by microscopy, but 2 of 11 (18.2%) samples were still positive by PCR. Thirty negative controls were all found to be PCR negative, and 15 positive controls were all PCR positive. Cross-reactions with Mycobacterium leprae could be ruled out. In conclusion, PCR with inguinal lymph node or skin aspirates is suitable for confirming the clinical diagnosis of PKDL. In some patients, lymph node aspirates are probably preferred because aspiration of material from the skin may leave scars.     

Species identification of mycobacteria in paraffin-embedded tissues: frequent detection of nontuberculous mycobacteria.

Diagnosis of infections caused by mycobacteria, especially nontuberculous mycobacteria still represents a difficult task both in microbiology and pathology. The aim of this study was to determine the frequency of mycobacterial DNA detectable by PCR in formalin-fixed paraffin-embedded tissues showing suspicious granulomatous lesions. A total of 190 archival specimens were analyzed, using a nested PCR protocol, which amplifies a fragment of the mycobacterial 65-kDa heat-shock protein gene. Restriction fragment-length polymorphisms and sequencing were utilized to further analyze the obtained PCR products. Corresponding microbiological culture results were available for 41 cases. We detected mycobacterial DNA in 119 cases (63%), of which 71 (60%) were positive for Mycobacterium tuberculosis complex DNA and 41 (34%) for DNA of nontuberculous mycobacteria. Seven cases (6%) could not be subtyped for technical reasons. The largest group of nontuberculous mycobacteria comprised 29 cases (25% of the 119 positive cases), which were assigned to Mycobacterium fortuitum complex. Mycobacterium avium-intracellulare complex was detected in eight (7%) cases, Mycobacterium gordonae in three (2.5%) and Mycobacterium rhodesiae in a single case (0.8%). All cases of Mycobacterium tuberculosis were unequivocally identified by restriction fragment-length polymorphism analysis. In contrast, sequencing provided a gain of information over restriction fragment-length polymorphism analysis in 37% of the nontuberculous mycobacteria cases (15 of 41). Alignment studies on DNA of nontuberculous mycobacteria showed frequent sequence variations, supporting the existence of sequevars. Comparison of molecular data to available results of microbiological culture assays showed a good concordance of 83%. In conclusion, amplification and sequencing of the mycobacterial 65-kDa heat-shock protein gene is an excellent tool for species identification of mycobacteria, especially nontuberculous mycobacteria, in formalin-fixed paraffin-embedded tissues.     

Does Neutralization of Gastric Aspirates from Children with Suspected Intrathoracic Tuberculosis Affect Mycobacterial Yields on MGIT Culture?

The microbiological confirmation of pulmonary tuberculosis in children relies on cultures of gastric aspirate (GA) specimens. Conventionally, GAs are neutralized to improve culture yields of mycobacteria. However, there are limited data to support this practice. To study the utility of neutralization of GAs with sodium bicarbonate in children with intrathoracic tuberculosis, a total of 116 children of either sex, aged 6 months to 14 years (median age, 120 months; interquartile range [IQR], 7 to 192 months), underwent gastric aspiration on 2 consecutive days. Gastric aspirates were divided into two aliquots, and only one aliquot was neutralized with 1% sodium bicarbonate. Both aliquots were processed for smear and culture examinations. Out of the 232 gastric aspirates, 12 (5.17%) were acid-fast bacilli (AFB) smear positive. There were no differences in smear positivity rates from samples with or without neutralization. The yield of Mycobacterium tuberculosis on a Bactec MGIT 960 culture system was significantly lower in the neutralized samples (16.3% [38/232]) than in the nonneutralized samples (21.5% [50/232]) (P = 0.023). There was no significant difference between the neutralized and the nonneutralized samples in time to detection using the MGIT 960 system (average, 24.6 days; IQR, 12 to 37 days) (P = 0.9). The contamination rates were significantly higher in the neutralized samples than in the nonneutralized samples (17.2% [40/232] versus 3.9% [9/232]) (P = 0.001). The agreement for positive mycobacterial culture between the two approaches was 66.5% (P = 0.001). Hence, we recommend that gastric aspirate samples not be neutralized with sodium bicarbonate prior to culture for M. tuberculosis.     

Comparison of in house polymerase chain reaction with conventional techniques for the detection of Mycobacterium tuberculosis DNA in granulomatous lymphadenopathy

AIMS: To evaluate the usefulness of the devR based polymerase chain reaction (PCR) in the detection of Mycobacterium tuberculosis in lymph node aspirates and tissues of lymphadenitis and to compare PCR with conventional diagnostic techniques. SUBJECTS AND METHODS: Coded specimens of fine needle aspirates and biopsies from 22 patients with tuberculous lymphadenitis, 14 patients with non-tubercular lymphadenitis, and nine patients with granulomatous lymphadenitis were processed and subjected to analysis by PCR, smear microscopy, M tuberculosis culture, histology, and cytology. RESULTS: Tuberculous lymphadenitis was correctly diagnosed by PCR in 18 patients, by culture in five patients, by histology in 13 patients, and by cytology in seven patients. PCR gave two false positive results in 14 patients with non-tubercular lymphadenitis. The sensitivity of the conventional techniques was significantly higher with biopsies (17 of 22 specimens; 77%) than with fine needle aspirates (nine of 22 specimens; 41%). However, the sensitivity of PCR was not significantly higher with biopsies (68%) in comparison with fine needle aspirates (55%). The sensitivity of either biopsy PCR or fine needle aspirate PCR was not significantly different from that of either histology combined with culture or cytology combined with culture. The overall combined specificity of PCR was 86%. Mycobacterium tuberculosis DNA was detected in six of nine patients with granulomatous lymphadenitis. CONCLUSION: PCR is the most sensitive single technique available to date for the demonstration of M tuberculosis in specimens derived from patients with a clinical suspicion of tuberculous lymphadenitis. The value of PCR lies in its use as an adjunct test in the diagnosis of tuberculous lymphadenitis, particularly in those patients where conventional methods fail. Because fine needle aspiration is not an invasive procedure, it is the procedure of choice, and PCR should be performed initially on these samples. Excisional biopsy histology and PCR should be recommended only for patients in whom fine needle aspirate PCR is negative or when there is discrepancy with the clinical impression.     

Diagnosis of mycobacterial infections by nucleic acid amplification: 18-month prospective study.

We have investigated the use of DNA amplification by PCR for the detection of mycobacteria in clinical specimens, with the gene encoding the 16S rRNA as a target. Following generic amplification of mycobacterial nucleic acids, screening was done with genus-specific probe; this was followed by species differentiation by use of highly discriminating probes or nucleic acid sequencing. In a prospective 18-month evaluation, criteria to select specimens for PCR analysis were defined. Of a total of 8,272 specimens received, 729 samples satisfied the criteria and were subjected to DNA amplification. Clinical specimens included material from the respiratory tract (sputa and bronchial washings), aspirates, biopsies, and various body fluids (cerebrospinal, pleural, peritoneal, and gastric fluids). After resolution of discrepant results, the sensitivity of the PCR assay was 84.5%, the specificity was 99.5%, the positive predictive value was 97.6%, and the negative predictive value was 96.4%. The sensitivity and negative predictive value of culture (with a combination of broth and solid media) were 77.5 and 94.8%, respectively. In conclusion, this PCR assay provides an efficient strategy to detect and identify multiple mycobacterial species and performs well in comparison with culture.     

Modified immunohistological staining allows detection of Ziehl-Neelsen-negative Mycobacterium tuberculosis organisms and their precise localization in human tissue

The diagnosis of mycobacterial infection depends on the Ziehl-Neelsen (ZN) stain, which detects mycobacteria because of their characteristic acid-fast cell wall composition and structure. The histological diagnosis of tuberculosis (TB) comprises various aspects: (1) sensitive detection of mycobacteria; (2) precise localization of mycobacteria in the context of granulomatous lesions; (3) 'staging' of disease according to mycobacterial spread and granulomatous tissue integrity. Thus, detection of minute numbers of acid-fast bacteria in tissue specimens is critical. The conventional ZN stain fails to identify mycobacteria in numbers less than 10(4) per ml. Hence many infections evade diagnosis. PCR is highly sensitive, but allows neither localization within tissues nor staging of mycobacterial disease, and positive findings frequently do not correlate with disease. In this study, an anti-Mycobacterium bovis bacille Calmette-Guérin polyclonal antiserum (pAbBCG) was used to improve immunostaining, which was compared to the ZN stain in histological samples. Screening of tissue samples including lungs, pleural lesions, lymph nodes, bone marrow, and skin for mycobacterial infection revealed that pAbBCG staining detects infected macrophages harbouring intracellular mycobacteria or mycobacterial material as well as free mycobacteria that are present at low abundance and not detected by the ZN stain. The positive pAbBCG staining results were confirmed either by PCR analysis of microdissected stained tissue or by culture from tissue. This immunostaining approach allows precise localization of the pathogen in infected tissue.     

Fine needle aspiration in retroperitoneal lesions

The retroperitoneal space is a potential space extending from lumbar to the pelvic region, behind the peritoneum. It encloses many vital organs like adrenals, kidneys, ureters, pancreas, aorta and its branches, inferior vena cava and its tributaries and many lymph nodes along with loose connective tissue and fat. The literature regarding role of fine needle aspiration cytology (FNAC) for diagnosis of retroperitoneal lesions as a whole, is exceedingly limited. The present study was conducted to elucidate the spectrum of retroperitoneal lesions and to determine the diagnostic accuracy of fine needle aspiration cytology, presenting to a tertiary care referral centre. A total of 389 aspirates from retroperitoneal lesions were reviewed for clinical and radiological details. The smears were studied for the cytological diagnosis. Cytological–histological correlation was assessed and the causes for discordant diagnoses were determined. The patients’ age ranged from 1 to 88 years. There were 234 (60.2%) males and 155 (39.8%) females. In 61 (15.7%) aspirations, the yield was inadequate for reporting and 328 were satisfactory. About 113 (29.0%) aspirates were from pancreatic masses alone, 97 (24.9%) from the retroperitoneal lymph nodes, 70 (17.9%) from the kidneys, 45 (11.5%) from the adrenals, 41 (10.5%) from the retroperitoneal soft tissues and 23 (5.9%) from retroperitoneal segments of the gut. There were 249 (64.0%) neoplastic lesions and 79 (20.3%) non‐neoplastic lesions, the ratio being 3.1:1. Eight (2.0%) aspirates were reported as suspicious for malignancy, and 5 (1.2%) aspirates were reported as neoplastic but could not be categorized as benign or malignant. Of the neoplastic lesions, malignant neoplasms (n = 216; 87.1%) were much more common than the benign (n = 20; 8.0%), the ratio being 10.8:1. Of all the satisfactory aspirates, subsequent histopathology was available only in 33/327 (10%) cases. A positive correlation between cytological and histological diagnosis was observed in 27/33 (81.8%) cases. We believe FNAC is a useful method for an early, rapid, minimally invasive and reliable pre‐operative diagnosis for retroperitoneal lesions and can often obviate the need for open surgical biopsy.     

Diagnosis of disseminated mycobacterial infection in AIDS patients by US-guided fine needle aspiration biopsy of lymphnodes and spleen

Our aim was to evaluate the efficacy of abdominal US and fine-needle aspiration biopsy (FNAB) in the diagnosis of disseminated mycobacteriosis (DM) in patients with Acquired Immunodeficiency Syndrome (AIDS). We reviewed the US and clinical records of 18 AIDS patients (12 males; 22-43 years) with DM studied with abdominal US. 18 patients underwent fine-needle aspiration biopsy of enlarged abdominal lymphnodes and 11 underwent FNAB of the spleen. All aspirates were studied with acid-fast stain for fast examination and cultures for isolation of mycobacteria. Abdominal US showed: enlarged abdominal lymphnodes (diameter range: 5-35 mm; mean 17 mm) splenomegaly (spleen diameter range: 14-22 cm; mean: 16.2 cm) and hepatomegaly (right hepatic lobe thickness range: 14.5-18.5 cm) in all patients; multiple splenic abscesses (diameter range: 3-20 mm) in 11 patients; small intestine wall thickening in 5 patients (maximum bowel wall thickness range: 7-15 mm); mild to moderate ascites in 8 patients; pleural effusion in 4 patients; hyperechogenicity of the kidney cortex in 5 patients; peritoneal abscesses in one and a retroperitoneal abscess in one patient. fast-acid-stain of spleen and/or lymphnode FNAB specimens allowed early diagnosis of mycobateriosis in 18/18 cases (100%). Cultures of lymphnode aspirates grew mycobacteria in 10/18 patients (56%). Spleen aspirates grew mycobacteria in 11/11 patients (100%) Blood cultures were positive in 6/18 patients (33%). Diagnosis of species was M. tuberculosis in 9 and M. avium in 6 patients. In 3/18 patients (17%) all cultures were negative. In conclusion, abdominal US features suggest DM in AIDS patients. Spleen and/or lymphnode FNAB allows a specific diagnosis in 100% of the patients.