Cytogenetics of lymphomas

Cytogenetic analysis is now a routine part of the diagnosis and management of a significant number of lymphoid malignancies. Whilst conventional cytogenetics remains the most comprehensive method for assessing chromosome abnormalities, the technical difficulties associated with conventional cytogenetics in most lymphomas has resulted in increased use of fluorescence in situ hybridisation (FISH) to identify specific abnormalities that are useful in either the diagnosis or management of these disorders. The finding of one of the Burkitt's translocations is of major importance in the diagnosis of Burkitt's and Burkitt's-like lymphomas, whereas the t(14;18), although seen in most follicular lymphomas (FL), is not usually required to make a diagnosis. Thus, whilst cytogenetics may be of interest in FL, it is not an essential part of the diagnostic work-up. Conventional cytogenetics may be useful for identifying markers of resistance to Helicobacter pylori therapy in MALT lymphomas. In disorders such as Hodgkin lymphoma, hairy cell leukaemia and lymphoplasmacytoid lymphoma, although many cytogenetic abnormalities have been observed, no consistent or specific abnormalities have been identified and so, at this point in our knowledge of the genetics of these disorders, cytogenetics cannot be considered a useful test for either diagnosis or prognosis.In contrast, the diagnosis of mantle cell lymphoma is now dependent upon the identification of the 11;14 translocation that results in cyclin D1 up-regulation. It is widely acknowledged that FISH is the most consistently useful test to identify the juxtaposition of the CCND1 and IGH genes in mantle cell lymphoma and is regarded as the 'gold standard'. FISH also has a role in identifying genetic abnormalities of prognostic significance in chronic lymphocytic leukaemia. Given the wealth of genetic and cytogenetic abnormalities that are continuing to be found in chronic lymphoid malignancies, it will be some time before the optimal use of both conventional cytogenetics and FISH is established in the diagnosis and management of lymphomas.     

Immunohistochemistry as an aid in the diagnosis of Hirschsprung's disease

The interpretation of rectal suction mucosal biopsies taken for the purpose of ruling out Hirschsprung's disease (HD) can be especially difficult in neonatal patients because of ganglion cell (GC) immaturity. Acetylcholinesterase histochemistry on frozen sections can be helpful but requires experience and may be complicated by excessive mucosal hemorrhage. The authors retrospectively have studied 27 patients, including 11 patients with HD, on whom conventionally fixed and embedded tissue was available, using an immunoperoxidase system directed against neuron-specific enolase (NSE) and S100 protein. NSE immunostaining produced intense staining of GC perikarya, greatly facilitating recognition of small immature forms. S100 immunostaining also highlighted GC as prominent negative stained cells surrounded by the positivity of Schwann cells. Both stains were helpful in demonstrating the overall pattern of microinnervation and its relationship to possible GC. The authors conclude that NSE and S100 immunostaining may facilitate interpretation of rectal mucosal biopsies when Hirschsprung's disease is being considered as a possibility.     

Tetrazolium medium as an aid in the routine diagnosis of Candida

The tetrazolium medium described is easily prepared and serves as a rapid, relatively accurate and simple means of differentiating Candida species, particularly C. albicans, from other yeasts. Culture on this medium does not replace other techniques used for yeast identification. No one test alone will suffice and final identification must rest on an overall pattern of characteristics. In the screening of 1,822 yeast isolates in this laboratory, culture on this medium has proved a valuable adjunct to other recognized techniques, and is now in regular use.     

Serum alkaline phosphatase fractionation as an aid to diagnosis

A case is reported in which the serum alkaline phosphatase reached high levels, and in which the differential diagnosis between hepatic secondary deposits and osteomalacia proved difficult by the usual means. Separation of the alkaline phosphatases by starch grain electrophoresis was used as an aid to differential diagnosis.     

Complement fixation test as an aid in the diagnosis of farmer's lung.

Complement-fixing antibodies to Micropolyspora faeni were measured in farmers and controls. Farmers with known or suspected farmer's lung showed significantly higher titers than control groups. Variations in titer were measured and correlated with the clinical disease.     

Cytokeratin expression as an aid to diagnosis in medical liver biopsies

Bateman A C & Hübscher S G
(2010) Histopathology 56 , 415–425
Cytokeratin expression as an aid to diagnosis in medical liver biopsies The study of cytokeratin expression has provided a valuable insight into the biliary microanatomy of the liver in health and disease. The canals of Hering are a putative site of origin for progenitor cells, which may repopulate the liver after cellular damage and loss. Normal bile ducts and the bile ductular reaction that occurs in many chronic liver diseases – especially chronic biliary tract disease – express cytokeratin (CK) 7 and CK19. Therefore, both ductopenia and the process of bile ductular reaction can be highlighted with immunohistochemistry for these cytokeratins. Furthermore, CK7 is usually expressed in an increasingly widespread manner by hepatocytes as chronic cholestatic liver disease progresses. For these reasons, CK immunohistochemistry is a very useful adjunct to morphological assessment and histochemical stains for copper retention when a diagnosis of chronic biliary disease is being considered. This review describes the anatomical theory behind the use of CK immunohistochemistry for the assessment of bile duct number and distribution in the liver and provides practical advice for the application of this technique in the diagnostic setting of common medical liver diseases.     

Tuberculosis of the cervix: cytology as an aid to diagnosis.

Two cases of tuberculous cervicitis are presented. The presence in cervical smears of both epithelioid and Langhans' giant cells, which are described, should raise a strong suspicion of tuberculosis.     

Transferrin analysis by immunofixation as an aid in the diagnosis of cerebrospinal fluid otorrhea

Laboratory diagnosis of cerebrospinal fluid leakage has been unreliable and has required expensive, labor-intensive radiographic procedures. Recently, using protein electrophoresis and immunofixation, the presence of an isoform of transferrin present only in cerebrospinal fluid has been identified. We describe the value of this simple test in a patient with recurrent meningitis in whom repeated radiographic studies failed to demonstrate a leak.     

The use of an expert system in the clinical laboratory as an aid in the diagnosis of anemia

Experience with an expert system developed for the purpose of classification of anemias is presented. Input for this system consists of limited demographic information on each patient and the results of the complete blood count, with the incorporation of the results of further chemical testing (serum iron/total iron binding capacity/ferritin and serum B12/serum folate/red blood cell folate), if indicated. Performance of this system is demonstrated using data from 84 patients seen in the authors' laboratory selected either because of a request for evaluation by the attending physician or because of significant anemias. Using this limited input, the system was able to accurately classify 74 of 84 (88%) of cases according to previously established criteria. The output from the system is overread by a pathologist. Future directions are also discussed.     

Detection of tissue CEA-like substance as an aid in the differential diagnosis of malignant mesothelioma

Sections of various adenocarcinomas and malignant mesotheliomas were tested for carcinoembryonic antigen (CEA) localized in tissues by the immunoperoxidase technique; epithelial mucin was demonstrated with the PAS technique. While CEA and mucin were found in many adenocarcinomas, both were absent in the 43 cases of malignant mesothelioma we investigated. In the problem of distinguishing between adenocarcinoma and mesothelioma, the CEA-test in combination with conventional strains for mucin is a useful technique and clearly identifies most adenocarcinomas. A dual negative result for CEA and mucin, although not proving that a given lesion is a mesothelioma, adds considerable support to this histological diagnosis.     

Diffusion-weighted imaging as an aid in the diagnosis of the etiology of medial longitudinal fasciculus syndrome

Purpose

Internuclear ophthalmoplegia is caused by a lesion; stroke, multiple sclerosis, brain metastases, or trauma may produce lesions of the medial longitudinal fasciculus (MLF). Imaging techniques, such as DWI, can help identify the site of the lesion in order to speed diagnosis and lead to appropriate treatment.

Methods

Over an 8-month period, eight consecutive patients with suspected MLF syndrome (most secondary to ischemic stroke) underwent MRI examinations, including DWI sequencing, at an academic center in Taiwan.

Results

In all eight patients, abnormal high-signal lesions were found close to the floor of the fourth ventricle on the dorsal side of the pons. A neuroanatomical comparison showed that the location of the lesions was identical to the anatomical position of the MLF.

Conclusion

Using DWI, good clinico-radiological correlation was found in all eight ischemic stroke patients diagnosed with MLF syndrome. DWI may broaden the application of MRI in the diagnosis of MLF syndrome.