Nodal melanocytic nevi in sentinel lymph nodes. Correlation with melanoma-associated cutaneous nevi

Melanocytic nevi occurring in lymph nodes create diagnostic difficulty by mimicking metastases. Few studies describe nodal nevi in sentinel lymph nodes (SLNs) excised for melanoma. We evaluated 72 cases in which patients had undergone SLN biopsy for melanoma. Lymph nodes and cutaneous melanomas were evaluated according to a standard protocol. Nodal nevi were identified in 8 patients (11%). Of these, 6 (75%) had an associated cutaneous nevus (P = .006). Of 21 patients with an associated nevus, 4 (19%) with nodal nevi had a cutaneous nevus with congenital features (P = .01). The incidence of nodal nevus correlated with a Breslow thickness greater than 2.5 mm (P = .02). Nevi were not seen in non-SLNs. Nodal nevi appear more frequently in patients with melanoma-associated cutaneous nevi, particularly if congenital features are present. The increased frequency of nodal nevi in SLNs relative to non-SLNs suggests an etiology of mechanical transport of nevus cells.     

Histopathological patterns of melanoma metastases in sentinel lymph nodes

AIMS: Sentinel lymph node biopsy (SLNB) is an important component in the staging and treatment of cutaneous melanoma (CM). The medical literature provides only limited information regarding melanoma sentinel lymph node (SLN) histology. This report details the specific histological patterns of melanoma metastases in sentinel lymph nodes (SLNs) and highlights some key factors in evaluating SLNs for melanoma. METHODS: From 281 SLNB cases between June 1998 and May 2002, 79 consecutive cases of SLN biopsies positive for metastases from CM were retrospectively reviewed. The important characteristics of the SLNs and the metastatic foci are described. RESULTS: The median size of positive SLNs was 17 mm (range, 5-38). SLNs had a median of two metastatic foci (range, 1-11), with the largest foci being a median of 1.1 mm in size (range, 0.05-24). S-100 and HMB-45 staining was positive in 100% and 92% of the detected metastatic foci, respectively. The metastatic melanoma cells were epithelioid, spindled, and mixed in 86%, 5%, and 9% of cases. Metastatic foci were most often (86%) found in the subcapsular region of the SLN. Benign naevic cells were found coexisting in 14% of positive SLNs. CONCLUSIONS: Staining for S100 is more sensitive than HMB-45 (100% v 92%), but HMB-45 staining helped to distinguish benign naevic cells from melanoma. The subcapsular region was crucial in SLN evaluation, because it contained the metastases in 86% of cases. Evaluation of the subcapsular space should not be compromised by cautery artefacts or incomplete excision of the SLN.     

Sentinel lymph nodes in cutaneous melanoma: the experience in the Florence area

In the period 1997-2001, 466 sentinel lymph nodes from 342 lymphatic basins in 322 melanoma patients were examined at the Health Unit of Florence. The lymphatic mapping was performed through pre-operative lymphoscintigraphy using technetium-labelled nano-colloid, intradermal injections of vital blue dye and intra-operative gamma-probe. The examined patients were 182 females and 140 males. Sentinel lymph node was one in 65.2% of cases; two sentinel lymph nodes were detected in 27% of cases and more than 2 sentinel nodes were detected in 7.8% of cases. Melanoma metastases in one or more sentinel lymph nodes were found in 61/322 patients (18.9%). Lymphatic basins resulted to be involved by melanoma metastases were 64/342 (18.7%); sentinel lymph nodes containing metastatic melanoma deposits were 73/466 (15.6%). No metastasis was found in patients with melanoma thickness < or = 1 mm. One or more positive sentinel lymph nodes were found in 7.5% of patients with melanoma thickness > 1.00 and < or = 1.50 mm, in 27.7% of patients with melanoma > 1.50 and < or = 3.00 mm, in 38.2% of patients with melanoma > 3.00 and < or = 4.00, and in 60.7% of patients with melanoma > 4.00 mm. Frozen section analysis of sentinel lymph nodes, performed in 59/61 patients with nodal metastases, detected nodal involvement in 21 patients (35.6%). Metastases were identified by routine hematoxylin-eosin staining in 57/64 positive lymphatic basins; in 7 cases (11%) metastases were detected by immunohistochemical stainings (S100 and HMB-45). A nodal nevus was found in 3/466 sentinel lymph nodes (0.6%). Our data are analyzed and compared to previously data of the literature. The value of frozen section analysis and the major problems in the diagnosis of melanoma micrometastases in sentinel lymph nodes are discussed. The importance of the sentinel node biopsy for the detection of occult metastases and for the correct staging of melanoma patients are stressed, according to the new TNM melanoma classification.     

Intraoperative cytologic evaluation of sentinel lymph nodes in patients with breast carcinoma by scrape preparation

Intraoperative evaluation of sentinel lymph nodes (SLNs) in patients with breast carcinoma allows surgeons to complete axillary lymph node dissection in one procedure if any SLN shows metastasis. The accuracy of intraoperative pathological diagnosis is critical for decision-making. The purpose of this study was to evaluate our rapid intraoperative cytologic diagnosis of SLN through comparing with the final surgical pathologic diagnosis of the corresponding lymph nodes. A total of 454 SLNs from 159 consecutive female patients with a preoperative diagnosis of breast carcinoma over 3-year period were included in this study. After gross examination of each bisected lymph node, a scrape preparation was prepared for each submitted lymph node and was stained by the rapid Papanicolaou method. The intraoperative cytologic diagnosis was compared with the final surgical pathologic diagnoses. The overall sensitivity of intraoperative cytology was 52.5% with specificity of 100%. There were 17 false-negative cases. Of them, six nodes had isolated tumor cells, seven nodes had micrometastasis (0.2-2 mm), and four nodes had macrometastasis (>2 mm). There were no interpretive errors identified. The size of metastasis and tumor grade appeared to be significant factors in detecting metastasis by cytology. In addition, subsequent non-SLN involvement was 9% in patients with micrometastasis versus 50% in patients with macrometastasis (P < 0.05). Our study shows that the intraoperative cytologic evaluation of SLNs in breast carcinoma is a reasonably accurate method. The majority of false-negative cases were due to micrometastasis and isolated tumor cells.     

Pathologic evaluation of sentinel lymph nodes in colorectal carcinoma

BACKGROUND: The identification of lymph node metastases in colorectal resection specimens is necessary for accurate tumor staging. However, routine lymph node dissection by the pathologist yields only a subset of nodes removed surgically and may not include those nodes most directly in the path of lymphatic drainage from the tumor. Intraoperative mapping of such sentinel lymph nodes (SLNs) has been reported in cases of melanoma and breast cancer. We applied a similar method to cases of colorectal carcinoma, with emphasis on the pathology of the SLNs. METHODS: Eighty-three consecutive patients with colorectal carcinoma were evaluated after intraoperative injection of 1 to 2 mL of 1% isosulfan blue dye (Lymphazurin) into the peritumoral subserosa. Blue-stained lymph nodes were suture-tagged by the surgeon within minutes of the injection for identification by the pathologist, and a standard resection was performed. Designated SLNs were sectioned at 10 levels through the block; a cytokeratin immunostain (AE1) was also obtained. To evaluate the possibility that increased detection of metastases in the SLN might be solely due to increased histologic sampling, all initially negative non-SLNs in the first 25 cases were sectioned also at 10 levels. RESULTS: Sentinel lymph nodes were identified intraoperatively in 82 (99%) of 83 patients and accounted for 152 (11.9%) of 1275 lymph nodes recovered, with an average of 1.9 SLNs per patient. A total of 99 positive lymph nodes (38 positive SLNs and 61 positive non-SLNs) were identified in 34 node-positive patients. The SLNs were the only site of metastasis in 17 patients (50%), while 14 patients (41%) had both positive SLNs and non-SLNs. Three patients (9%) had positive non-SLNs with negative SLNs, representing skip metastases. In patients with positive SLNs, 91 (19%) of 474 total lymph nodes and 53 (12%) of 436 non-SLNs were positive for metastasis. In patients with negative SLNs, 8 (1%) of 801 total lymph nodes and 8 (1.2%) of 687 non-SLNs were positive for metastasis. Multilevel sections of 330 initially negative non-SLNs in the first 25 patients yielded only 2 additional positive nodes (0. 6%). All patients with positive SLNs were correctly staged by a combination of 4 representative levels through the SLN(s) together with a single cytokeratin immunostain. CONCLUSIONS: Intraoperative mapping of SLNs in colorectal carcinoma identifies lymph nodes likely to contain metastases. Focused pathologic evaluation of the 1 to 4 SLNs so identified can improve the accuracy of pathologic staging.     

In breast cancer patients sentinel lymph node metastasis characteristics predict further axillary involvement

The aim of the study was to correlate various primary tumor characteristics with lymph node status, to examine sentinel lymph node (SLN) metastasis size and non-SLN axillary involvement, to look for a cut-off size/number value possibly predicting additional axillary involvement with more accuracy and to examine the relationship of SLN metastasis size to overall survival. Of 301 patients who underwent SLN biopsy, 75 had positive SLNs. The size of the metastases was measured. For different size categories, association with the prevalence of non-SLN metastases was assessed. Associations between metastasis size and tumor characteristics and overall survival (OS) were studied. The prevalence of axillary lymph node (ALN) involvement was not significantly different between cases with micrometastasis or macrometastasis in SLNs (p?=?0.124). However, for metastases larger than 6, 7, and 8 mm, the prevalence of ALN involvement was significantly higher (p?=?0.046, 0.022, and 0.025). OS was significantly lower in SLN-positive than in SLN-negative cases (p?=?0.0375). Primary tumor size larger than 20 mm was associated with a significantly higher incidence of SLN metastasis (p?<?0.001), and primary tumor size over 26 mm was associated with additional positive non-SLN (p?<?0.001). Higher mitotic index (≥7) in primary tumors was significantly (p?<?0.001) associated with ALN involvement in SLN-positive cases, whereas higher Ki67 labeling index was not significantly correlated with SLN or ALN involvement. Lymphovascular invasion (LVI) in primary tumors was significantly correlated with SLN positivity (p?<?0.001) but not with further ALN involvement or OS. Tumor size and LVI are predictive for SLN metastasis. Mitotic index, primary tumor size, and larger volume SLN involvement are determinants of further ALN involvement. SLN metastasis size over 6 mm is a strong predictor of further axillary involvement. OS is shorter in the presence of positive SLN.     

Non-sentinel lymph node involvement in patients with breast cancer and sentinel node micrometastasis; too early to abandon axillary clearance

AIMS: It has been suggested that patients with T1-2 breast tumours and sentinel node (SLN) micrometastases, defined as foci of tumour cells smaller than 2 mm, may be spared completion axillary lymph node dissection because of the low incidence of further metastatic disease. To gain insight into the extent of non-sentinel lymph node (n-SLN) involvement, SLNs and complementary axillary clearance specimens in patients with SLN micrometastases were examined. METHODS: A set of 32 patients with SLN micrometastases was selected on the basis of pathology reports and review of SLNs. Five hundred and thirteen n-SLNs from the axillary clearance specimens were serially sectioned and analysed by means of immunohistochemistry for metastatic disease. Lymph node metastases were grouped as macrometastases (> 2 mm), and micrometastases (< 2 mm), and further subdivided as isolated tumour cells (ITCs) or clusters. RESULTS: In 11 of 32 patients, one or more n-SLN was involved. Grade 3 tumours and tumours > 2 cm (T2-3 v T1) were significantly associated with n-SLN micrometastases as clusters (grade: odds ratio (OR), 8.3; 95% confidence interval (CI), 1.4 to 50.0; size: T2-3 tumours v T1: OR, 15; 95% CI, 2.18 to 103.0). However, no subgroup of tumours with regard to size and grade was identified that did not have n-SLN metastases. CONCLUSIONS: In patients with breast cancer and SLN micrometastases, n-SLN involvement is relatively common. The incidence of metastatic clusters in n-SLN is greatly increased in patients with T2-3 tumours and grade 3 tumours. Therefore, axillary lymph node dissection is especially warranted in these patients. However, because n-SLN metastases also occur in T1 and low grade tumours, even these should be subjected to routine axillary dissection to achieve local control.     

Metastatic melanoma volume in sentinel nodes: objective stereology-based measurement predicts disease recurrence and survival

Aims:  Sentinel lymph node (SLN) status is the most important prognostic factor in intermediate thickness melanoma. The amount of metastatic disease in positive SLNs varies greatly between patients, and this tumour burden appears to influence the prognosis of node-positive patients. The aim was to use objective stereological techniques to correlate accurately total SLN tumour burden with recurrence and patient survival.
Methods and results:  SLNs from 327 patients were examined by complete step sectioning and immunohistochemistry. The total metastasis volume (TMV) of 156 positive SLNs from 99 patients (30.3%) was measured using stereological methods based on the 2D-nucleator and Cavalieri's principle. The maximum metastasis diameter was also measured. These two measurements were correlated with disease recurrence and patient survival. The mean TMV for SLN+ patients was 10.5 mm³ (median 0.05 mm³; range 0.0001–623.7 mm³). Median follow-up was 26.3 months. On multivariate analysis, TMV was an independent predictor of recurrence when corrected for primary tumour thickness ( P  = 0.001) and was a stronger prognosticator compared with the maximum metastasis diameter ( P  < 0.0001 versus P  = 0.01).
Conclusions:  Combining total step sectioning of SLNs with stereological assessment of metastases, we found metastasis volume to be a highly significant predictor of disease recurrence and survival.     

Frozen section analysis of sentinel lymph nodes in patients with breast cancer does not impair the probability to detect lymph node metastases

Intra-operative frozen section analysis (FS analysis) of sentinel lymph nodes (SLNs) in patients with breast cancer can prevent a second operation for axillary lymph node dissection. In contrast, loss of tissue during FS analysis may impair the probability to detect lymph node metastases. To determine the effect of tissue loss on the probability of detection of metastases, dimensions and tissue loss resulting from intra-operative frozen section analysis were measured for 21 SLNs. In a mathematical model, the influence of tissue loss on the probability to detect metastases was calculated in relation to SLN size for various pathology protocols: an American, a widely used European, the extensive ‘Milan’ and the Dutch protocol. For median-sized SLN 11 × 8 × 5 mm (length × width × height), FS analysis led to a median loss of 680 μm (13.6%) of the height of the SLN. Irrespective of SLN size or used pathology protocol, the probability of detecting 2 mm metastases remained unchanged or even increased (0–12.8%). Moreover, the probability to detect 0.2 mm metastases increased for the majority of tested combinations of SLN size, tissue loss and used protocol. Only when combining maximum tissue loss and smallest SLN size in the Dutch protocol, or when applying the extensive Milan protocol on a median-sized SLN, the probability to detect 0.2 mm metastases decreased by 2.7% and 14.3%, respectively. Contrary to ‘common knowledge’, doing FS analysis of SLNs does not impair the probability to detect lymph node metastases.     

Anatomo-pathologic study of sentinel lymph nodes in melanoma. Analysis of 200 cases

Pathologic evaluation of sentinel lymph node represents a new technique for managing high-risk primary melanoma. We examined the sentinel lymph node biopsies of 200 patients affected by primary melanomas of trunk, limbs, head and neck, who had been operated at "M. Bufalini" Hospital between April 1996 and July 1998. The lymphatic mapping has been performed through the preoperative intradermal injection of vital blue dye and technetium-labelled albumin. 319 sentinel lymph nodes were harvested and the 11.3% (15% of patients) were positive for melanoma metastases. No metastases were found in melanomas < or = 1 mm. The percentage of positive sentinel lymph nodes in patients with melanomas > 1 mm in thickness was 16.3% (22% of patients). In 5 cases (2.5%) nodal nevi were found, 1 of which was associated with micrometastasis. All 30 patients with positive sentinel lymph nodes underwent regional lymph node dissection and 555 lymph nodes were harvested. Melanoma metastases were found in only 7 patients, in 31 lymph nodes. The procedure of SLN detection and biopsy is a feasible surgical approach to melanoma patients. It is extremely useful in finding early metastases and in effective pathologic staging. As a consequence of the very low incidence of metastases in the sentinel lymph nodes of patients with thin melanomas, we suggest the sentinel lymph node mapping should be offered to patients with primary melanomas at least 1 mm in depth.     

Detection of micrometastases in bone marrow and sentinel lymph nodes of breast cancer patients

Objective: To study the sensitivity and clinical significance of HE-staining,IHC and RT-PCR in detecting breast cancer micrometastases in bone marrow and sentinel lymph nodes (SLNs). Methods:After general anesthesia, all patients underwent bone marrow puncture and sentinel lymph node biopsy (SLNB) by 1% isosulfan blue, and then HE-staining,IHC and RT-PCR were used to detect micrometastases. Results:Of 62 patients with breast cancer whose axillary lymph nodes showed negative HE-staining results, 15 cases presented with positive RT-PCR and 9 cases showed positive IHC results positive in bone marrow micrometastases detection. PT-PCR and IHC showed good uniformity(kappa=0.6945)and there was significant difference in detective rate between these two methods (χ2=4.1667,P=0.0412). In SLN samples, 13 showed positive RT-PCR results, while 7 showed positive IHC results. PT-PCR and IHC showed good uniformity (kappa=0.6483)and significant difference was also found in detective rate between these two methods (χ2=4.1667,P=0.0412). Both bone marrow and SLN samples were RT-PCR positive in 3 cases,which indicated that bone marrow micrometastases did not always accompany SLN micrometastases(χ2=0.067,P=0.796). Conclusion: Even if no axillary lymph node involvement or distant metastases are present in routine preoperative examination, micrometastases can still be detected in bone marrow or SLNs. Because the bone marrow micrometastases and axillary node micrometastses are not present simultaneously, combination test of multiple indicators will detect micrometastases more accurately.     

A model for determining the optimum histology of sentinel lymph nodes in breast cancer

AIMS: To create and use a geometrical model for sentinel lymph node (SLN) histopathology in breast cancer. METHODS: The model involves a spherical metastasis randomly situated in an SLN. Two extreme situations are taken as the starting points. In one of these, the metastasis is seen in its largest dimension, whereas in the other it is only just visible, approximating 0 mm in size. Intermediate positions are analysed, with different metastasis sizes and different distances between the levels assessed by histology. RESULTS: The findings suggest that sections taken 1 mm apart afford a reasonable means of identifying almost all metastases measuring > 2 mm (referred to as macrometastases here). For nearly all micrometastases to be identified correctly according to the current TNM definitions (that is, metastases > 0.2 mm), a step sectioning protocol with levels of 250 microm or 200 microm would be adequate. CONCLUSIONS: SLNs are the most likely sites of nodal metastasis. Macrometastases are of recognised prognostic relevance so that all should be identified, preferably correctly as macrometastases; an assessment of levels 1 mm apart appears satisfactory and sufficient for this aim. SLNs also offer an ideal method for the study of the significance of micrometastases; for this, step sections separated by 200 or 250 microm are a good choice.     

False-positive cells in sentinel lymph nodes

Melanoma sentinel lymph nodes (SLN) are carefully evaluated to maximize sensitivity. Examination includes hematoxylin and eosin (H+E) stained sections at multiple levels through the node, with subsequent immunohistochemical (IHC) stains for melanocytic markers if H+E sections are negative for melanoma. However, not all IHC-positive cells in SLN are metastatic melanoma, as evidenced by the presence of MART-1 positive cells in SLN from breast cancer patients with no history of melanoma (so-called 'false-positive' cells). These 'false-positive cells' could be nodal nevus, non-melanocytic cells with cross-reacting antigenic determinants, phagocytic cells containing melanocyte antigens, or possibly melanocytes or melanocyte stem cells liberated at the time of biopsy of the cutaneous melanoma. Examination of SLN requires careful correlation of H+E and IHC findings.     

Mapping metastases in sentinel lymph nodes of breast cancer

Localization of metastases within the sentinel lymph nodes (SLNs) of breast cancer has not been studied. Forty SLNs from 36 patients with operable primary breast cancers were identified by means of lymphatic mapping with patent blue dye. The junction between the patent blue-stained lymphatic vessel draining the tumor and the SLN was labeled with alcian blue. Metastases within the serially sectioned SLNs were assigned to the alcian blue-labeled side, to the opposite side of the virtually halved nodes, or both. Eight SLNs were negative for metastasis. Eleven SLNs had metastases only in the blue half. Only 4 cases had larger metastases in the nonblue half. Metastases are more likely to be located in the vicinity of the inflow junction of the identifiable lymphatic draining the tumor and the SLN. This should be considered when SLNs are examined, especially when they are halved for different studies.     

Histopathological work-up and interpretation of sentinel lymph nodes removed for vulvar squamous cell carcinoma

Aims:  To evaluate the work-up of sentinel lymph nodes (SLNs) removed for vulvar pT1–pT2 squamous cell carcinoma (SCC). Inguinal lymphadenectomy yields metastases in only 30% of cases. Patients with missed inguinal disease, however, have a risk of dying from systemic disease. SLN dissections reduce morbidity, but work-up should reliably identify metastatic disease.
Methods and results:  All SLNs removed from 38 patients with pT1–pT2 SCC and clinically negative inguinal lymph nodes were submitted for frozen section analysis. When negative, SLN were formalin-fixed, sectioned entirely at 330-μm intervals to produce three slides per millimetre [two haematoxylin and eosin (H&E) stained slides; one slide for immunohistochemistry]. If screening of H&E-stained sections was negative, all remaining slides were subjected to immunohistochemistry with an antibody to cytokeratin. Twenty-five of 38 patients (66%) were pN0, 7/38 (18%) had metastases on frozen sections/H&E stains. Immunohistochemistry detected micrometastases in two patients and single tumour cells and anucleate cell structures in four patients. In 12/13 patients the SLN metastases, including all single-cell deposits, were from lichen sclerosus (LS)-associated SCC. Twelve of 13 patients with metastases had a pT2 SCC.
Conclusions:  Micrometastases and single tumour cell deposits in SLNs are typical of LS-associated vulvar SCC. Single tumour cell deposits in SNLs should be regarded as 'positive'. Identification requires serial sectioning and immunohistochemical analysis of all removed SLNs.     

Rapid immunohistochemistry of sentinel lymph nodes for metastatic melanoma

Sentinel lymph node (SLN) biopsy is performed on patients with malignant melanoma (MM) to assess the need for selective complete lymphadenectomy. Melanoma metastasis to regional lymph nodes is an important prognostic indicator in patients with MM. This study assesses the sensitivity and specificity of rapid immunohistochemistry (RIHC) in intraoperative delineation of melanoma metastasis to SLN. RIHC for S-100 protein, HMB45, and a melanoma marker cocktail (melan A, HMB45, and tyrosinase) was performed on 71 SLNs obtained from 28 patients with MM. Frozen sections (6 micro thick) on plus slides were fixed for 2 to 3 minutes in cold acetone and then stored at -70 degrees C. The EnVision kit (Dako, Carpinteria, CA) for rapid immunohistochemistry (RIHC) on frozen tissue sections was used, and the staining technique took 19 minutes. Together with preparation of the frozen sections and fixation in acetone, immunostained slides were available in approximately 25 minutes. Of the 71 SNLs examined, 7 showed melanoma metastasis in permanent sections. RIHC of frozen sections detected metastatic melanoma in 6 SLNs, with a sensitivity of 86% for HMB45 and 71% for S-100 protein and the melanoma cocktail and a specificity of 97% for HMB45 and 100% for S-100 and the melanoma cocktail. We conclude that RIHC for HMB45, S-100 protein, and the melanoma cocktail may help detect melanoma metastasis in SLN intraoperatively, leading to total lymph node dissection and obviating the need for 2 surgical procedures. Section folds and background stain can make interpretation difficult. Intraoperative time constraints require a more rapid technique. A recent consensus group has discouraged frozen-section examination of SLN.     

p16 expression in sentinel nodes with metastatic breast carcinoma: evaluation of its role in developing triaging strategies for axillary node dissection and a marker of poor prognosis

Not all patients with metastatic breast carcinoma (MBC) in a sentinel lymph node (SLN) have metastasis in additional axillary nodes (ANs). A biological marker that can predict this occurrence may be beneficial in triaging only appropriate patients for AN dissection (AND). Our aim was to study p16 expression in SLNs and to determine whether it is a predictor of metastases to additional ANs and a marker of poor prognosis. We correlated p16 expression in SLNs and ANs of 54 patients with MBC with clinicopathologic features and the nodal proliferative index (PI). We sequenced p16 from DNA in 7 cases. We found that 35 of 54 cases (65%) had p16-positive tumor cells. Nine of 17 (53%) cases in which both SLN and AND were done had MBC in additional ANs. The SLNs of 8 of 9 cases (89%) were p16 positive (73% positive predictive value). Eight of 17 (47%) cases had no metastases in ANs even though their SLNs had metastases. The SLNs of 5 of 8 (62.5%) of these cases were p16 negative (83% negative predictive value). Ductal MBCs were p16 positive in 27 of 37 cases (73%). Carcinomas with a lobular component were p16 negative in 9 of 11 cases (82%). Nine of 12 (75%) p16-negative ductal carcinomas were estrogen receptor (ER) positive. Some 75% of T2 and T3 tumors were p16 positive, compared with 50% of T1 tumors. The highest PI (defined as > or =50%) was seen in p16-positive SLNs (5 of 6 cases). The p16 DNA sequence was normal, and no mutations were found. Our findings indicate that p16 expression in SLNs with MBC predicts (1) increased likelihood of metastasis in additional ANS, and its expression along with other markers and clinicopathologic parameters may serve as an indicator for proceeding to a formal AND; (2) poor prognosis and is associated with larger primary tumors with a high nodal PI and ER-negative status; and (3) histological subtypes. Gene mutations were not responsible for the expression of p16 in our cases.     

Diagnostic value of HMB-45 and anti-Melan A staining of sentinel lymph nodes with isolated positive cells.

Numerous immunohistochemical stains have been employed to detect metastatic melanoma in sentinel lymph node (SLN) biopsies. HMB-45 is considered by some as a specific tool to detect early metastatic melanoma (1). Occasionally, one or two isolated HMB-45-positive cells may cause complications in diagnostic interpretation. The goal of this study was to evaluate the reliability of HMB-45 staining of SLNs with sparse isolated positive cells and to compare its staining with anti-Melan A antibody. HMB-45 and anti-Melan A antibody immunostaining was performed on (Group A) 15 histologically negative SLNs excised from patients with malignant melanoma (MM) and on (Group B) 15 histologically negative SLNs excised from patients with breast carcinoma (BC). None of the patients had clinical evidence of systemic metastasis at the time of SLN biopsy. Five cutaneous biopsies with changes of postinflammatory hyperpigmentation (PIHP) were also stained with both antibodies. HMB-45 staining was repeated in all Group B SLNs after blocking endogenous biotins. Electron-microscopic studies were performed on all cases of PIHP. Isolated HMB-45-stained cells were present in 6 of 15 SLNs removed for MM; 8 of 15 for BC; and 3 of 5 cutaneous biopsies of PIHP. HMB-45 reactivity persisted after blocking endogenous biotins in 6 of 8 positive SLNs from Group B. Anti-Melan A antibody was negative in all SLNs of group A and B and in dermal melanophages of all five cases of PIHP. HMB-45 positivity was demonstrated in histologically negative SLNs and cutaneous biopsies, especially in the milieu of aggregated melanophages. Phagocytosis of premelanosomes by macrophages in the draining lymph nodes may account for isolated cell positivity and can hinder correct diagnostic interpretation. HMB-45 may not be a reliable marker for the detection of micro-metastasis of MM and requires correlation with other immunohistochemical markers, such as anti-Melan A antibody, to enhance specificity.