The value of S-100 immunostaining as a diagnostic tool in human malignant melanomas. A comparative study using S-100 and neuron-specific enolase antibodies

Growing role of S100B protein as a putative therapeutic target for neurological- and nonneurological-disorders

S100B is a calcium-binding protein mainly expressed by astrocytes, but also localized in other definite neural and extra-neural cell types. While its presence in biological fluids is widely recognized as a reliable biomarker of active injury, growing evidence now indicates that high levels of S100B are suggestive of pathogenic processes in different neural, but also extra-neural, disorders. Indeed, modulation of S100B levels correlates with the occurrence of clinical and/or toxic parameters in experimental models of diseases such as Alzheimer's and Parkinson's diseases, amyotrophic lateral sclerosis, muscular dystrophy, multiple sclerosis, acute neural injury, inflammatory bowel disease, uveal and retinal disorders, obesity, diabetes and cancer, thus directly linking the levels of S100B to pathogenic mechanisms. In general, deletion/inactivation of the protein causes the improvement of the disease, whereas its over-expression/administration induces a worse clinical presentation. This scenario reasonably proposes S100B as a common therapeutic target for several different disorders, also offering new clues to individuate possible unexpected connections among these diseases.

Immunohistochemical Reactivity of the Antimelanoma Monoclonal Antibody Mel-1

The immunohistochemical reactivity of the monoclonal antimelanoma antibody MEL-1 was evaluated on frozen sections of 9 malignant melanomas, 5 nevi, 1 squamous cell carcinoma, 1 basal cell carcinoma, 2 benign dermal fibrous histiocytomas, 1 infiltrating ductal and 2 infiltrating lobular carcinomas of the breast, 1 primary squamous cell carcinoma and 1 adenocarcinoma of the lung, 1 lung metastasis of gastric adenocarcinoma, 1 adenocarcinoma of the large bowel, 1 lymph node, 1 case of malignant histiocytosis and one of lymph nodal immunoblastic lymphoma, and 1 biopsy of oral cavity mucosa. In primary and metastatic malignant melanoma, junctional nevi, and the upper half of compound and dermal nevi, the staining was intense. Also, benign dermal fibrous histiocytoma and the case of lymph nodal malignant histiocytosis showed an intense reactivity, whereas the immunostaining positivity of the squamous cell carcinoma of the skin, the lung adenocarcinoma, the squamous cutaneous and mucosal epithelium, and the sweat and sebaceous glands was slight. In ductal and lobular infiltrating carcinoma of the breast only focal areas or isolated tumor cells were positive. The lack of reactivity of deep dermal melanocytes of compound and dermal nevi may be correlated with a different antigenic phenotype of the melanocytes. After discussion of the technical problems, the application of MEL-1 was suggested, for diagnostic purpose, to identify lymph nodal metastases in cases of primary self regressed malignant melanoma and to detect lymph nodal metastatic microfoci of malignant melanoma.

Immunohistochemistry in the era of personalised medicine

BACKGROUND

Immunohistochemistry (IHC) plays a central role in the histopathological classification of diseases, including cancer. More recently, the importance of immunohistochemical staining is increasing. IHC usage in diagnostics is invaluable; however, the genetic and therapeutic significance of biomarker immunostaining has become equally relevant.

CONTENT

In this article, we would like to analyse the three distinct roles of IHC and review their individual impacts on modern diagnostic pathology: (1) diagnostic IHC; (2) genetic IHC and (3) therapeutic IHC.

SUMMARY

Thus, we will characterise the different analytical processes that are required in the three approaches to IHC usage stated above, as well as the clinical significance and overall importance in patient management. This will allow us to hypothesise on the most appropriate laboratory environment and detection methods for the future.

Sox10 is expressed in primary melanocytic neoplasms of various histologies but not in fibrohistiocytic proliferations and histiocytoses

BACKGROUND

Sox10 is a transcription factor associated with neural crest development. Its expression has been reported in melanocytes and peripheral nerve sheath cells and their associated tumors.

OBJECTIVE

To assess Sox10 sensitivity in benign and malignant melanocytic neoplasms of various histologic subtypes and to discern the specificity of Sox10 in distinguishing between melanocytic neoplasms and fibrohistiocytic and histiocytic mimickers.

METHODS

Sox10 expression was examined by immunohistochemistry in 145 cases of formalin-fixed paraffin-embedded tissue, including benign and malignant melanocytic lesions of various histologies and stages (n = 83), fibrohistiocytic and histiocytic lesions (n = 33), and peripheral nerve sheath tumors (n = 19), among others (n = 10).

RESULTS

Immunoreactivity with Sox10 was observed in 100% (83/83) of benign and malignant melanocytic lesions of various subtypes, as well as in 100% (19/19) of benign and malignant peripheral nerve sheath lesions. Among the fibrohistiocytic proliferations and histiocytoses examined, Sox10 was negative in all cases (0/33). Sox10 expression did not vary by histologic subtype in nevi or melanoma; however, both the percentage of tumor nuclei demonstrating Sox10 expression and the intensity of expression were inversely correlated with malignant potential (nevi, melanoma in situ, invasive and metastatic melanoma) (P < .001, P = .016, respectively). Malignant peripheral nerve sheath tumors also showed decreased mean Sox10 expression and decreased intensity of expression when compared with benign counterparts (P < .001, P = .021, respectively).

LIMITATIONS

This is a retrospective study with 145 cases included.

CONCLUSIONS

Sox10 is a highly sensitive marker for melanocytic proliferations and may be useful diagnostically when the differential diagnosis includes fibrohistiocytic and histiocytic proliferations demonstrating S100 expression.

The S100B protein in biological fluids: more than a lifelong biomarker of brain distress

S100B is a calcium-binding protein concentrated in glial cells, although it has also been detected in definite extra-neural cell types. Its biological role is still debated. When secreted, S100B is believed to have paracrine/autocrine trophic effects at physiological concentrations, but toxic effects at higher concentrations. Elevated S100B levels in biological fluids (CSF, blood, urine, saliva, amniotic fluid) are thus regarded as a biomarker of pathological conditions, including perinatal brain distress, acute brain injury, brain tumors, neuroinflammatory/neurodegenerative disorders, psychiatric disorders. In the majority of these conditions, high S100B levels offer an indicator of cell damage when standard diagnostic procedures are still silent. The key question remains as to whether S100B is merely leaked from injured cells or is released in concomitance with both physiological and pathological conditions, participating at high concentrations in the events leading to cell injury. In this respect, S100B levels in biological fluids have been shown to increase in physiological conditions characterized by stressful physical and mental activity, suggesting that it may be physiologically regulated and raised during conditions of stress, with a putatively active role. This possibility makes this protein a candidate not only for a biomarker but also for a potential therapeutic target.

In vitro screening and structural characterization of inhibitors of the S100B-p53 interaction

S100B is highly over-expressed in many cancers, including malignant melanoma. In such cancers, S100B binds wild-type p53 in a calcium-dependent manner, sequestering it, and promoting its degradation, resulting in the loss of p53-dependent tumor suppression activities. Therefore, S100B inhibitors may be able to restore wild-type p53 levels in certain cancers and provide a useful therapeutic strategy. In this regard, an automated and sensitive fluorescence polarization competition assay (FPCA) was developed and optimized to screen rapidly for lead compounds that bind Ca(2+)-loaded S100B and inhibit S100B target complex formation. A screen of 2000 compounds led to the identification of 26 putative S100B low molecular weight inhibitors. The binding of these small molecules to S100B was confirmed by nuclear magnetic resonance spectroscopy, and additional structural information was provided by x-ray crystal structures of several compounds in complexes with S100B. Notably, many of the identified inhibitors function by chemically modifying Cys84 in protein. These results validate the use of high-throughput FPCA to facilitate the identification of compounds that inhibit S100B. These lead compounds will be the subject of future optimization studies with the ultimate goal of developing a drug with therapeutic activity for the treatment of malignant melanoma and/or other cancers with elevated S100B.

HMB-45, S-100, NK1/C3, and MART-1 in metastatic melanoma

The diagnosis of melanoma metastatic to lymph node remains a difficult problem given its histological diversity. We examined the staining patterns of S-100, NK1/C3, HMB-45, and MART-1 (DC10) in melanoma metastases to lymph nodes. Immunohistochemical stains were performed on tissue sections of 126 formalin-fixed lymph nodes from 126 patients with an established diagnosis of metastatic melanoma. A total of 98% of cases (123 of 126) stained positive for S-100, 93% (117 of 125) stained positive for NK1/C3, 82% (103 of 126) stained positive for MART-1, and 76% (95 of 125) stained positive for HMB-45. The distribution and intensity of staining varied among these markers. A diffuse staining pattern, defined as >50% of tumor cells stained, was observed in 83% of MART-1-positive cases but in only 56% of S-100-positive cases, 48% of NK1/C3-positive cases, and 34% of HMB-45-positive cases. A maximally intense signal was almost always observed for MART-1 (83% of positive cases) but was rarely observed for NK1/C3 (20%). S-100 and HMB-45 showed maximally intense staining in 50% and 54% of cases, respectively. S-100 and NK1/C3 stained both histiocytes and melanocytes, whereas MART-1 and HMB-45 stained only melanocytes. Seventy-eight cases (63%) stained positive for all 4 markers, 17 cases (14%) stained for all markers except HMB-45, 13 cases (10%) stained for all markers except MART-1, 6 cases (5%) stained only with S-100 and NK1/C3, 4 cases (3%) stained only with S-100 and HMB-45, and 2 cases stained for all markers except S-100. One case each stained for the following: only S-100, only S-100 and HMB-45, and all markers except NK1/C3. One case exhibited absence of staining for any of these markers. We demonstrate that lymph node metastases of melanoma are heterogeneous with regard to tumor marker expression. S-100 and NK1/C3 were the most sensitive stains for detecting metastatic melanoma; however, they both also stain other nontumor cells in lymph nodes. MART-1 did not stain histiocytes and exhibited a more frequently intense and diffuse staining pattern than NK1/C3. HMB-45 was less sensitive and demonstrated less diffuse staining than MART-1.

Immunohistochemistry in the diagnosis of soft tissue tumours

Immunohistochemistry is particularly important in the field of soft tissue tumours because of their variety and the frequent difficulty of diagnosis. The first part of this paper discusses useful or new antibodies, together with others that are no longer of use. The second part is devoted to the role of immunohistochemistry in the diagnosis of soft tissue tumours: identification of some rare or atypical benign lesions, identification of non-mesenchymal malignant tumours, and classification of sarcomas. The respective roles of immunohistochemistry and molecular biology are underlined.

Canine balloon and signet-ring cell melanomas: a histological and immunohistochemical characterization

Seven tumours that were composed of balloon (n=4) or signet-ring (n=3) cells were investigated for a putative melanocytic origin. The tumours were located in the skin or the mouth cavity. In one case a sample from inguinal lymph node metastasis was available. Two antibodies used in man for the immunohistochemical diagnosis of melanomas, namely anti-Melan-A and anti-tyrosinase, were examined for their cross-reactivity with the corresponding canine antigens. The Melan-A antibody labelled all balloon cell tumours and one signet-ring cell tumour, whereas the anti-tyrosinase antibody was not reactive in any of the tumours. The Melan-A antibody also labelled a variety of canine epithelioid and spindle cell melanomas; non-melanocytic tumours were all negative. This study confirmed the occurrence of balloon and signet-ring cell melanomas in dogs. Melan-A antibody was found to be useful in the diagnosis of pigmented and non-pigmented canine melanomas.

A panel immunoblot using co-incubated monoclonal antibodies for identification of melanoma cells

Antigen expression in melanoma is heterogeneous. Immunophenotyping using a panel of monoclonal antibodies may facilitate immunotherapy. An immunoblot procedure was developed to detect antigens in melanoma cells. Numerous monoclonal antibodies were tested to determine if (1) antigens were detected after transfer to membranes, (2) single bands or discrete multiple bands were obtained, (3) co-incubation of multiple monoclonal antibodies had no interference, and (4) banding patterns were non-overlapping. Antigens were selected based upon their association with melanoma and the availability of respective monoclonal antibodies. Antigens were melanoma antigen recognized by T-cells (MART-1), tyrosinase, tyrosinase-related protein 1 (TRP-1), S100, vimentin, glycoprotein 130 (gp130), a carcinoembryonic antigen (CEA)-like marker, KBA-62 and NKI-C3. Actin positive controls could be assessed simultaneously. Test samples were separated by polyacrylamide gel electrophoresis in a 4-15% polyacrylamide gradient, transferred to polyvinylidine fluoride membrane, blotted using a Fast-Blot apparatus (Pierce), and developed using diaminobenzidine/metal. Melanoma cell lines were immunophenotyped using this panel immunoblot, and were compared to a standard control and to non-melanoma cells. Up to four antigens could be detected simultaneously in a single lane of the immunoblot, using a single test sample of greater than 100000 cells.

Microphthalmia transcription factor expression in cutaneous benign, malignant melanocytic, and nonmelanocytic tumors

The protein encoded by the microphthalmia (mi) gene is a transcription factor essential for the development and survival of melanocytes. Using a monoclonal antibody generated against human Mi transcription factor protein (Mitf) the authors previously demonstrated that Mitf expression is conserved in primary and metastatic malignant melanomas, and appears to be a highly sensitive and specific melanocytic marker. Mitf expression in various cutaneous nevi and cutaneous nonmelanocytic tumors has not been documented systematically. The authors evaluated Mitf immunostaining in 62 benign nevi, 58 primary cutaneous melanomas, and 53 nonmelanocytic tumors. Mitf immunostaining was conserved in all benign nevi, with Spitz nevi and neurotized nevi demonstrating decreased staining intensity. With the exception of desmoplastic melanomas, all primary cutaneous melanomas were immunopositive regardless of the cell type. Only one of 14 desmoplastic melanomas was Mitf positive. None of the nonmelanocytic tumors was immunopositive, including those lesions that may resemble melanoma histologically (spindle cell carcinomas, atypical fibroxanthomas, and leiomyosarcomas). The results demonstrate that Mitf antibody expression is conserved in the majority of benign and malignant melanocytic lesions, and that it may be helpful in the diagnosis of primary melanocytic skin lesions. Its use in desmoplastic melanomas is limited and is reflective of other melanocyte-associated antigens. Mitf discriminates between spindle cell nonmelanocytic tumors and melanomas with a spindle cell morphology, and is useful in a panel with other appropriate antibodies.

Expression of melan-A (MART1) in benign melanocytic nevi and primary cutaneous malignant melanoma

The Melan-A (MART1) gene encodes an antigen recognized by cytotoxic T cells. Although its expression in metastatic melanoma has been documented in the literature by several investigators, little is known about its distribution in primary melanomas and benign melanocytic nevi. In this study, we evaluated Melan-A expression immunohistochemically on sections from paraffin-embedded material of 50 benign nevi and 40 primary cutaneous melanomas using the monoclonal antibody A103. To evaluate a potential role of A103 in the differential diagnosis of melanocytic from nonmelanocytic tumors, we also analyzed a number of benign and malignant peripheral nerve sheath tumors, fibrohistiocytic tumors, and leiomyosarcomas. Immunoreactivity with A103 was present in all "nonneurotized" nevi and in all nondesmoplastic primary melanomas, both in the intraepidermal and the dermal component. Only two nevi that underwent prominent neurotization showed no staining with A103. Although all melanomas with epithelioid cells tended to be strongly positive with A103, only 4 of 13 spindle cell and desmoplastic melanomas (all positive with anti-S-100 and negative with HMB-45) were immunoreactive with A103 (two focally, two diffusely). None of the nonmelanocytic lesions expressed Melan-A. Our results confirm that Melan-A protein is broadly expressed in the majority of benign and malignant melanocytic lesions and suggest that A103 can be helpful diagnostically, not only for metastatic tumors, but also for primary skin lesions. Its use in distinguishing between melanocytic and peripheral nerve sheath tumors, however, is limited because of the low or absent expression of Melan-A in nevi that underwent neurotization and spindle cell and desmoplastic melanomas.

Immunoreactivity for A103, an antibody to melan-A (Mart-1), in adrenocortical and other steroid tumors

The Melan-A (MART-1) gene encodes an antigen recognized by cytotoxic T cells. It has been said to be restricted in its expression to melanocytes. However, here we report the presence of immunoreactivity for A103, an antibody to Melan-A, in five adrenocortical adenomas, 16 primary and 13 metastatic adrenocortical carcinomas, four Leydig cell tumors of the testis, and three Sertoli-Leydig cell tumors of the ovary. To evaluate the potential diagnostic role of this antibody, we studied immunoreactivity for A103 in 111 carcinomas, 40 germ cell tumors, and 33 miscellaneous nonmelanocytic epithelioid tumors. All of them were negative for A103. Our findings suggest that once melanoma is excluded, A103 can aid in the recognition of steroid hormone-producing tumors and may be particularly useful in the diagnosis of adrenocortical carcinoma. The presence of immunoreactivity for A103 practically excludes any other carcinoma that may enter into the differential diagnosis of adrenocortical tumors.

Desmoplastic and spindle-cell malignant melanoma. An immunohistochemical study

The clinical, histologic, and immunohistologic features of 22 desmoplastic melanomas (DMM), 10 mixed desmoplastic and spindle-cell melanomas (DMM/SMM), and two cellular spindle-cell melanomas (SMM) were studied. Patients ranged in age from 35 to 91 years (mean, 67) and included 23 men and 11 women. Seventeen cases occurred in sun-damaged skin of the head and neck. 11 were on the extremities, and six on the trunk. Except for two cases, all were Clark's level IV or V. Twenty-two (65%) cases were associated with a recognizable overlying pigmented lesion. Thirty of 32 (94%) DMM and DMM/SMM were clearly positive for S100. S100 staining was limited to < 5% of the spindle cells in two DMM/SMM. All DMM were negative when stained with HMB45. Three DMM/ SMM were immunoreactive with HMB45, as were both SMM. CD68 staining was limited to < 5% of the spindle cells in two of 32 DMM and DMM/SMM and 20% of the cells in one of two SMM. Nine (32%) DMM and DMM/SMM contained significant numbers of spindle cells immunoreactive for SMA but not desmin. In five cases, the number of actin-positive spindle cells. Two color stains for SMA and S100 demonstrated that these smooth-muscle actin positive cells constituted a separate spindle-cell population, consistent with reactive myofibroblasts. This study indicates that the immunohistologic features of desmoplastic melanoma differ from those of conventional melanoma. If a problematic spindle-cell skin lesion is a suspected melanocytic process, HMB45 is unlikely to provide confirmatory (or exclusionary) evidence for the diagnosis of DMM. Similarly, because of the variability in S100 expression in this neoplasm, the absence of S100 staining should not be relied on too heavily to exclude DMM if the clinical and histologic features favor that diagnosis. Caution should be exercised in the interpretation of numerous actin-positive spindle cells in isolation of additional confirmatory or exclusionary data as desmoplastic melanomas may contain significant numbers of these cells.

Evaluation of new putative tumor markers for melanoma

BACKGROUND

The early diagnosis of recurrent melanoma can contribute to better outcome if the disease can be surgically resected or if the metastases are responsive to systemic therapies. Lipid-associated sialic acid (LASA-P) and the S-100 protein (S-100) were evaluated as tumor markers for melanoma with the goal of early detection of recurrence.

METHODS

Sixty-seven patients were identified who had levels of S-100 and LASA-P drawn during their clinical course. A multivariate regression analysis was performed to determine the significance of the serum markers in relation to other prognostic factors for melanoma.

RESULTS

After a median follow-up of 30 months, 58 patients had recurrences, and 49 patients died of disease. LASA-P elevation was not associated with the time to recurrence (p = 0.2176) or survival (p = 0.2507). S-100 positivity was a significant predictor of recurrence (p < 0.0001) and survival (p = 0.0059). The median time to recurrence for S-100-positive and S-100-negative patients was 7.6 and 33.8 months, respectively. The median survival time was 59.2 months for S-100-negative patients and 29.6 months for patients positive for S-100.

CONCLUSIONS

Serum S-100 shows significant correlations to both time to recurrence and survival and could be useful in the clinical detection of malignant melanoma.

S100 protein positive human breast carcinomas: an immunohistochemical study

An immunohistochemical study for S100 protein was performed on 95 human breast carcinomas. S100 protein positive carcinoma cells were recognized in 54 cases (57%). The S100 protein positive and negative carcinomas were then compared in terms of stage, histologic type, nuclear grade, appearance of minute calcification, immunoreactivity for estrogen receptor (ER), tumor recurrent pattern, and prognosis. The S100 protein positive cases had a tendency to show a low nuclear grade (P < 0.01). They were also more often seen in the ER positive group. For further analysis of the nature of S100 protein positive carcinoma cells, immunoreactivity for neuron-specific enolase (NSE) and actin was investigated. The positive staining for NSE and actin was seen in 46 cases (48%) and 3 cases (3%), respectively. There was, however, no specific correlation among the S100 protein. NSE, or actin staining. The nature of S100 protein positive carcinoma cells still remains unclear. The S100 protein positive carcinomas, however, exhibit relatively better characteristics.

Immunohistochemical analysis of cutaneous malignant melanoma: comparison of S-100 protein, HMB-45 monoclonal antibody and NKI/C3 monoclonal antibody

Immunohistochemical analysis was carried out on 144 formalin fixed paraffin embedded cutaneous melanomas to ascertain the value of 3 different immune markers. The sensitivity and staining patterns regarding intensity and distribution, as well as correlation to pigment content, cell type, surface ulceration and host response was noted. The stains used were monoclonal HMB-45 (Dako product No M634), NKI/C3 antibodies (Biogenex product No MU077) and polyclonal rabbit anti S-100A protein (Dako product No L1845). Of the lesions tested, 63 were malignant melanoma with an adjacent component of superficial spreading type, 61 were malignant melanoma with no adjacent component, 2 were malignant melanoma with adjacent lentigo maligna, 8 were in situ with 7 superficial spreading melanoma and one lentigo maligna (HMF) and 10 were metastatic melanoma. All 144 lesions stained for S-100 (100% sensitivity). One hundred and thirty-seven stained for NKI/C3 (95%); 132 stained for HMB-45 (92% sensitivity). S-100 was the most sensitive marker and stained tumor cells diffusely. With HMB-45 and NKI/C3, though marginally less sensitive, staining was stronger and patchy. In addition, NKI/C3 showed a tendency for peripheral (membrane) staining. HMB-45 staining was directly proportional to the pigment content, with stronger staining of radial growth phase melanoma and negative staining of those lesions where pigment content was minimal or absent. Also, with HMB-45 a decrease in staining intensity with depth or vertical growth phase was observed. There was no relationship to cell type with HMB-45 but with NKI/C3, 5 out of the 7 that failed to stain showed spindle cell differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Desmoplastic malignant melanoma of the gingiva

A case of desmoplastic melanoma in a 58-year-old man is reported. This rare malignancy occurred in the maxillary alveolus, appearing as an epulis. Histologically, the tumor was flanked by melanocytic proliferation in the adjacent mucosae. At the time of local recurrence after partial maxillectomy, the tumor showed a polypoid growth, with an increase in cellularity and mitotic rate resembling spindle cell carcinoma. The value of immunostaining for diagnosis is stressed.

Balloon cell malignant melanoma of the skin. A clinicopathologic study of 34 cases with histochemical, immunohistochemical, and ultrastructural observations

Balloon cell malignant melanoma (BCMM) is a rare histologic variant of malignant melanoma (MM). Thirty-four patients with BCMM from the files of the Armed Forces Institute of Pathology (AFIP) were studied by means of clinicopathologic correlation and histochemical, immunohistochemical, and ultrastructural methods to better define this entity. The cytoplasmic features of the balloon cells observed in BCMM resemble those noticed in balloon cell nevus (BCN), but the presence of nuclear pleomorphism, atypia, and mitoses and the absence of intervening stroma help distinguish BCMM. The cells also show many histochemical, immunochemical, and ultrastructural features of conventional melanoma cells. Although it is generally believed that balloon melanoma cells represent a degenerative change, the immunohistochemical and electron microscopic findings suggest that the balloon tumor cells are most likely metabolically active melanocytic cells. Microscopically, BCMM also must be differentiated from other clear cell tumors such as clear cell sarcoma (MM of soft parts), hibernoma, xanthoma, sebaceous neoplasms, metastatic renal cell carcinoma, (malignant) clear cell acrospiroma, (malignant) granular cell tumor, granular (clear) cell basal cell carcinoma, clear cell syringoma, and atypical fibroxanthoma. The prognosis of BCMM usually correlates with the tumor thickness similar to that in other histologic types of cutaneous MM. Nineteen (57.5%) of 33 patients with adequate follow-up information died of disseminated tumors from 2 months to 12 years after the initial treatment. Six (18.2%) patients developed local recurrences: four of these patients died of metastasis and two were alive with metastatic tumor at last contact. Five (15.2%) patients were alive with metastatic tumors, and seven (21.2%) were alive without evidence of disease at last contact. Recognition of BCMM is important because of its malignant biologic behavior.

Symptoms of notalgia paresthetica may be explained by increased dermal innervation

Notalgia paresthetica is a sensory neuropathy characterized by infrascapular pruritus, burning pain, hyperalgesia, or tenderness. To assess whether the symptoms may be caused by alterations in the cutaneous innervation, skin from the affected area of patients (n = 5) was compared with controls (n = 10) comprising the contralateral unaffected area from the same patients and site-matched biopsies of normals, using immunohistochemistry. Frozen sections were immunostained with antisera to the neuropeptides substance P, calcitonin gene-related peptide, vasoactive intestinal polypeptide, and neuropeptide with tyrosine, and to the general neural marker PGP 9.5 and the glial marker S-100 to show the overall innervation and glial cells, respectively. No discernible change in the distribution of neuropeptide-immunoreactive axons was found, but all of the specimens from the affected areas had a significant increase in the number of intradermal PGP 9.5-immunoreactive nerve fibers compared with unaffected areas from the same patients and normal controls. Epidermal dendritic cells immunoreactive for S-100, possibly Langerhans cells, were substantially increased. It is concluded that there is an increase in the sensory epidermal innervation in the affected skin areas in notalgia paresthetica, which could contribute to the symptoms, and that neural immunohistochemistry of skin biopsies could be helpful in the diagnosis of the disease.

Evaluation of spindle cell tumors

The most important aspect of any evaluation of spindle cell tumors in the skin or superficial soft tissues is the clinical examination, as a great deal can be learned from the location, appearance, and size of the tumor in question. As recounted in this chapter, the histologic features of these tumors may also be distinctive; however, in some instances, histologic examination alone is insufficient for diagnosis. In such cases, electron microscopy holds considerable promise, but the technique is too dependent upon both the availability of adequately preserved tissues and access to the technique itself. As a result, immunohistochemistry remains the favored approach to most problematic lesions. In our experience, at least 90% of histologically enigmatic tumors will exhibit a characteristic immunophenotype, the remainder usually being indeterminant for a specific pattern of differentiation. The latter outcome is often the result of improper tissue preservation, but may also reflect the primitive nature of some neoplasms. Fortunately, the least common outcome is an ambiguous or "mixed-lineage" phenotype, in which neither one of two or more patterns of differentiation is resolved with certainty. The most common settings in which these problems arise are the separation of MPNST from LMS, and the recognition of melanocytic lesions as distinct from tumors of peripheral nerve sheath. The latter is clearly of greatest clinical concern, and should be the focus of additional study.

S100 protein in human mammary tissue--immunoreactivity in breast carcinoma, including Paget's disease of the nipple, and value as a marker of myoepithelial cells

The expression of S100 protein, as assessed by immunohistochemistry, has been evaluated in 101 mammary carcinomas of various histological types, including Paget's disease of the nipple. S100 immunoreactivity was seen in 44 of 101 primary carcinomas, including in situ lesions. It was present in all histological types, with the exception of mucoid carcinoma. In the 33 cases with associated Paget's disease of the nipple, S100 expression was seen in the Paget's cells in six cases. S100 immunoreactivity has been suggested as a marker of myoepithelial cells, but in our hands staining of these cells is less consistent using the S100 antibody than with antibodies to actin. Furthermore, S100 protein is also expressed by some luminal epithelial cells. Therefore, in contrast to actin immunoreactivity, S100 immunoreactivity is not a reliable means of differentiating between luminal epithelial and myoepithelial cells. The possibility that staining with antibody to S100 protein may be affected by methods of fixation and immunohistochemical technique is discussed.

A primary amelanotic melanoma of the vagina diagnosed by immunocytochemistry

A case of primary malignant melanoma of the vagina is discussed. The lesion consisted of a nodule in the middle third of the vagina that was histologically suspected of being an unpigmented malignant melanoma. The melanocytic origin of the lesion was confirmed by the pattern of reactivity to a battery of human melanoma associated antigens and to class 1 and 2 histocompatibility antigens. No secondary lesions or alternative primary sites were found. The patient underwent radical hysterectomy with bilateral salpingooophorectomy, total vaginectomy and vulvectomy, radical inguinal, pelvic and paraaortic lymphadenectomy. The pathology report showed the presence of multiple neoplastic foci in the vagina. Although the removed lymph nodes were histologically free of metastases, microscopic foci of neoplastic cells were detected by immunohistochemistry in three lymph nodes. There is no evidence of recurrence at the twelfth postoperative month. Our results show that immunohistochemical techniques may usefully complement diagnostic histopathology in the diagnosis of female genital tract melanoma.

Primary mucosal malignant melanoma: an immunohistochemical study of 12 cases with comparison to cutaneous and metastatic melanomas

Immunohistochemical analysis of 40 formalin-fixed, paraffin-embedded malignant melanomas (12 primary mucosal, 16 primary cutaneous, and 12 metastatic cutaneous) was performed to study the possible differences in immunostaining profiles according to location. The majority of melanomas were reactive with a polyclonal antibody to S100 protein (P-S100; 85%), a monoclonal melanoma-specific antibody (HMB-45; 88%), and a monoclonal antibody to vimentin (90%), and there were no differences in staining profiles for these antibodies by anatomic location. In contrast, while 13 of 16 cutaneous melanomas (81%) and ten of 12 metastatic melanomas (83%) were reactive with a monoclonal antibody to S100 protein (MoAb-079), only five of 12 mucosal tumors (42%) showed positive staining for MoAb-079. Similarly, 14 cutaneous melanomas (88%) and 11 metastatic melanomas (92%) showed positive staining for neuron specific enolase (NSE), while only four mucosal melanomas (33%) were NSE-positive. Of the 40 melanomas, all but two were reactive with either P-S100, MoAb-079, or HMB-45. These findings suggest that MoAb-079 and NSE may be less sensitive markers than P-S100 and HMB-45 for routinely processed mucosal melanomas as compared with cutaneous and metastatic tumors.

Neuroendocrine carcinoma (Merkel cell tumor?) presenting as a subcutaneous tumor. An ultrastructural and immunohistochemical study of three cases

The clinical and pathological features of three unusual soft tissue tumors are presented. They occurred in the groin of elderly patients in the subcutaneous tissue. In Case 1, the inguino-crural tumor coexisted with a second mass in the pelvis. The tumors had a tendency to recur locally and to invade the regional lymph nodes. Metastatic dissemination of the disease resulted in the death of the patient in Case 3. Histologically, the tumors appeared composed of small round cells with scanty cytoplasms, arranged in diffuse, poorly cohesive or solid sheets. In places, a trabecular pattern was noted. Mitotic figures were numerous. Some cells exhibited argyrophil granules. The ultrastructural study revealed compact whorls of intermediate filaments and neurosecretory granules. All three cases displayed a paranuclear dot-like positive reaction with antibodies to cytokeratins and neurofilaments. A diffuse cytoplasmic immunostaining for neuron-specific enolase was present in Cases 1 and 2. Protein S-100, vimentin and leucocyte common antigen could not be demonstrated. All these characteristics, except for the subcutaneous location, are shared with neuroendocrine (Merkel cell) tumors of the skin.

Prognosis of conjunctival melanomas in relation to histopathological features

Twenty-six patients (age 29-85 years) with primary malignant melanoma of the conjunctiva were analysed for usefulness of various histopathological and immunohistochemical features of the primary, recurrent and metastatic tumours in evaluating their prognosis. The mean follow-up time was 5.5 years, ranging from 8 months to 17 years. Eight patients developed metastases and seven have died. The mean time from diagnosis to death due to metastasis was 3.8 years (range 1-6 years). The site of the primary tumour seemed to be most closely correlated to high metastatic risk. Only two of the sixteen limbal melanomas metastasised, whereas two of the four bulbar, all three tarsal and the only diffuse primary tumour caused metastatic disease. Two of the metastasising primary tumours were less than 1.5 mm thick, but all exceeded 0.8 mm in thickness. The mitotic rate, the amount of inflammatory infiltrate, the cell type or the presence of adjacent intraepithelial involvement did not obviously correlate to treatment outcome. Furthermore, the expression of S-100 protein and neuron-specific enolase (NSE), both suggested to be prognostic indicators in cutaneous melanoma, did not correlate to the tendency of the conjunctival melanomas to recur or metastasise.

Distinction between metastatic melanoma and primary parotid gland carcinoma using monoclonal HMB 45 antimelanoma antibody: report of a case

A case of malignant melanoma primary of the facial skin presenting with pre-auricular and submandibular masses, both thought to be metastatic melanoma, is reported. The case illustrates the practical application of a recently developed and commercially available specific anti-melanoma monoclonal antibody, HMB 45, which is useful in distinguishing between metastatic melanoma to a submaxillary lymph node and a synchronous primary parotid, poorly differentiated adenocarcinoma. The value of specific anti-melanoma antibody in conjunction with an antibody panel that includes S100, keratin, and epithelial membrane antigen in the distinction of melanomas from anaplastic carcinomas is discussed.

Recognition of malignant melanoma by monoclonal antibody HMB-45. An immunohistochemical study of 200 paraffin-embedded cutaneous tumors

Antibodies to S-100 protein have been used widely as markers of malignant melanoma, despite abundant evidence that they are non-specific for this neoplasm. Hence, alternatives to these reagents are desirable in diagnostic dermatopathology. We evaluated the characteristics of a new monoclonal antibody (HMB-45) which does have putative specificity for melanoma, and compared it with a polyclonal anti-S-100 reagent in immunohistochemical staining of 67 melanomas of the skin and 133 non-melanomatous cutaneous neoplasms. All specimens were formalin-fixed and paraffin-embedded, and were studied with the avidin-biotin-peroxidase complex technique. HMB-45 labelled 62 of 67 melanomas, while anti-S-100 recognized all tumors of this type. On the other hand, S-100 also was expressed by 15 of the non-melanocytic neoplasms, all 133 of which were HMB-45-negative. The only cases of melanoma that were missed by the latter reagent were of the spindle-cell type. Hence, HMB-45 was 100% specific and 93% sensitive, relative to a diagnosis of malignant melanoma in paraffin sections. Epithelioid and small-cell neoplasms are reliably recognized by this antibody, but it would appear that spindle-cell melanomas must be detected by other immunohistochemical means.

Amelanotic melanoma: cases studied by Fontana stain, S-100 immunostain, and ultrastructural examination

We studied 15 cases of amelanotic melanoma by using light microscopy (in conjunction with Fontana staining and S-100 immunostaining) and electron microscopy. In 14 of the 15 cases, metastatic melanomas were present; 11 were associated with a history of pigmented primary melanoma. The Fontana stain was positive in 4 cases and negative in 11. The S-100 stain was positive in 13 cases and negative in 2. Of the 11 cases with negative Fontana stains, 9 were positive with the S-100 immunostain and 2 were negative. Electron microscopy showed melanosomes in 13 cases. Melanosomes were seen in the two cases with negative Fontana and S-100 staining. Although all stages of melanosomes were identified, generally the majority were immature melanosomes. This study demonstrates the difficulties associated with the histologic diagnosis of amelanotic melanoma. The Fontana stain may be helpful, and the S-100 stain is generally positive. Electron microscopy provided the only evidence for melanoma in two cases and is considered the most definitive method of diagnosis of amelanotic melanomas. These tumors generally produce some pigment and thus are called amelanotic by convention, not because pigmentation is totally absent.

Melanoma cell heterogeneity. A study of two monoclonal antibodies compared with S-100 protein in paraffin sections

Fifty-six formalin, Bouin's, and Carnoy's fixed, paraffin-embedded malignant melanomas (21 primary, 35 secondary), were studied by avidin-biotin complex immunohistochemistry using monoclonal antibodies (MoAb) HMB-45 and B1.1, comparing reactivity with polyclonal anti-S-100 protein. B1.1 (anti-CEA MoAb) was expressed in a minor percentage of cells of the invasive component of some primary melanomas, and weak to moderately in scattered metastic melanoma cells. MoAb HMB-45 prepared against melanocytic tumors reacted with over 90% of all tumors studied, being weakly reactive in one, and nonreactive in four metastases. This antibody stained some primary melanomas and their dysplastic nevus components in a heterogeneous manner, but was largely nonreactive in deep dermal nevus cells that were in association with invasive melanoma, enabling recognition of the deepest penetration of melanoma cells in the dermal nevus component. MoAb HMB-45 appears specific for melanoma cells, with no cross-reactivity with nonnevomelanocytic malignant tumors (unlike polyclonal anti-S-100 protein). MoAb HMB-45 is more sensitive in detecting malignant melanoma cell heterogeneity than anti-S-100 protein.

Nucleolar organizer regions in cutaneous tumours

A silver colloid technique to identify nucleolar organizer region associated protein (AgNOR) has been applied to 68 cutaneous tumours. Basal cell carcinomas, eccrine tumours, apocrine tumours, and hair follicle tumours had differences in their numbers of AgNORs; these appeared as small black dots in their nuclei. Dermatofibromas and squamous cell carcinomas showed a degree of variability in the number of AgNORs depending on the cellularity of the former and differentiation of the latter. Basal cell carcinomas possessed significantly many more AgNORs per nucleus than the other neoplasms. It is suggested that this technique, previously the province of the cytogeneticist, may be of use in the diagnosis of cutaneous neoplasms.

Leu-7 in small cell neoplasms. An immunohistochemical study with ultrastructural correlations

In an effort to delineate the distribution of the Leu-7 antigen in small cell neoplasms, 283 paraffin-embedded examples of such tumors were studied immunohistochemically. These included 125 malignant lymphomas, 94 neuroendocrine carcinomas, 13 adenocarcinomas, 14 squamous carcinomas, four malignant melanomas, six neuroblastomas, four nephroblastomas (Wilms' tumors), six primitive neuroectodermal neoplasms, three "Askin" tumors, ten Ewing's sarcomas, and four embryonal rhabdomyosarcomas. Histologic diagnoses were verified by the use of electron microscopic study or independent immunostains. Overall, 44% of small cell neuroendocrine carcinomas expressed Leu-7, whereas nonendocrine carcinomas were uniformly nonreactive for this determinant. All neuroblastomas yielded immunopositivity, as did three primitive neuroectodermal tumors, three rhabdomyosarcomas, two "Askin" tumors, one nephroblastoma, one Ewing's sarcoma, and one malignant melanoma. None of the small cell lymphomas were Leu-7 positive. These results suggest that Leu-7 is a specific neuroendocrine marker in cases of small cell carcinoma, but its sensitivity is lower than that of other "endocrine" determinants. Reactivity patterns for Leu-7 in other small cell tumors demonstrate no specificity for any given line of cellular differentiation. However, the shared expression of this antigen by neuroblastomas, neuroectodermal tumors, Ewing's sarcomas, and Wilm's tumors contributes further to the hypothesis that these neoplasms may be related histogenetically.

Diagnostic immunohistochemistry of canine round cell tumors

Sixty-five canine skin neoplasms studied using immunocytochemistry, included 22 histiocytomas, 18 amelanotic melanomas, 14 cutaneous lymphosarcomas, six mast cell tumors, and five transmissible venereal tumors. Formalin-fixed, paraffin-embedded sections were stained using the avidin-biotin-peroxidase complex (ABC) immunoperoxidase technique for reactivity with S-100 protein, kappa and lambda immunoglobulin light chains, alpha-1-antitrypsin, alpha-1-antichymotrypsin, leukocyte common antigen (LCA), neuron-specific enolase, keratin, cytokeratin, muramidase, and vimentin. Detection of S-100, kappa and lambda light chains, neuron-specific enolase, and vimentin were most useful for screening these neoplasms. None of the markers examined was consistent in staining histiocytomas. While reactivity of S-100 (ten cases) and neuron-specific enolase (ten cases) was detected in some amelanotic melanomas, lambda light chain immunoglobulin (eight cases) was relatively consistent in cutaneous lymphomas. Mast cell neoplasms reacted with avidin and, therefore, were positive, even on negative control sections. Vimentin reacted strongly on all amelanotic melanomas and transmissible venereal tumors examined. These antibodies are helpful adjuncts in the differential diagnosis of canine skin tumors.

S-100 protein positivity in breast carcinomas: a potential pitfall in diagnostic immunohistochemistry

S-100 protein, originally isolated from neural tissues, has also been identified in various normal and neoplastic cells, including malignant melanomas. A systematic immunohistochemical investigation of this antigen was performed on formalin-fixed paraffin-embedded samples of benign and malignant breast tissues with use of the avidin-biotin-peroxidase complex immunoperoxidase technique and a polyclonal antiserum that recognizes both the alpha and beta subunits of S-100 protein. In benign breast tissue, S-100 protein was present in both epithelial and myoepithelial cells of terminal ducts and lobules; the staining was cytoplasmic and sometimes nuclear. Of 100 randomly selected invasive breast carcinomas, 48 per cent contained S-100 protein-positive tumor cells. Lobular and medullary carcinomas (60 per cent and 80 per cent, respectively) were more frequently positive than ductal carcinomas (45 per cent). Dendritic cells, most likely Langerhans' cells, were present in some carcinomas and were also positive for S-100. There was no relationship of S-100 positivity to histologic differentiation, recurrence interval, or the expression of various tumor markers. The presence of S-100 protein positivity in metastatic breast carcinomas may lead to the erroneous diagnosis of malignant melanoma. Our observations underscore the importance of testing for a broad panel of tumor markers rather than relying on single antigens in evaluating metastatic malignancies of undetermined origin.

S-100 protein and neuron-specific enolase in cerebrospinal fluid and serum: markers of cell damage in human central nervous system

The development of a radioimmunoassay for S-100 protein is described. This method was used in combination with a recently developed radioimmunoassay for neuron-specific enolase in cerebrospinal fluid and serum from 47 patients with cerebral infarction, transient ischemic attack, intracerebral hemorrhage, subarachnoid hemorrhage, and head injury. In cerebrospinal fluid, increased concentrations of both S-100 and neuron-specific enolase were found after large infarcts, whereas after small infarcts and transient ischemic attacks, only neuron-specific enolase increased. The increased concentrations of S-100 and/or neuron-specific enolase were noted 18 hours to 4 days after cerebral infarction and transient ischemic attacks. Cerebrospinal fluid concentrations of these proteins also reflected the severity of the disease in patients with intracerebral hematoma, subarachnoid hemorrhage, or head injury. Temporal changes in serum S-100 and neuron-specific enolase concentrations reflected the clinical course in 4 patients. In stroke patients, the S-100 and neuron-specific enolase concentrations may reflect the extent of brain damage and could be useful in selecting patients with major stroke for more aggressive treatment during the acute phase.

Eccrine sweat gland carcinoma: an histologic and immunohistochemical study of 32 cases

In an attempt to characterize the immunocytochemical attributes of eccrine sweat gland carcinoma, we studied 32 examples of this tumor with antibodies to epithelial membrane antigen (EMA), cytokeratin (CK), carcinoembryonic antigen, S100 protein, alpha-lactalbumin, salivary amylase, blood group isoantigens, beta-2-microglobulin, and Leu M1. All cases expressed EMA and CK, and 28 of 32 cases also displayed at least 2 of the 6 remaining antigens. No significant variations were noted in the immunophenotypes of histologic subtypes of eccrine carcinoma. These results provide an objective means of diagnostic separation between sweat gland carcinoma and other primary malignant cutaneous tumors. However, they do not appear to correlate with the degree of tumoral differentiation, and are of no assistance in the separation of benign and malignant sudoriferous neoplasms. The ability of immunocytochemical techniques to distinguish between primary malignant adnexal cutaneous tumors and metastases to the skin appears unlikely, but remains to be studied further. Also, the use of immunostaining panels is advised in the study of adnexal carcinomas, since no single determinant in isolation is specific for these neoplasms.

Variations in S-100 protein expression in naevocellular naevi may be related to metabolic activity

Significant amounts of S-100 protein were demonstrated in naevus cells by an immunoperoxidase technique. Distribution of S-100 protein was similar in the various types of naevi tested. In most lesions, the superficial A-type naevus cells stained most heavily, while staining was weaker in the deeper B- and C-type naevus cells. The intensity of staining was not, however, homogeneous in the cells of the various layers of the naevus. S-100 protein was especially abundant in giant naevus cells which occurred in the vicinity of sub-epidermal A-type naevocytes. Cells from neurocutaneous melanosis contained extremely large amounts of S-100 protein. Normal melanocytes in the epidermis over dermal naevi contained variable amounts of S-100 protein, but mainly showed weak staining. However, in the basal epidermis of traumatized naevi there were many unusually large and partly dendritic melanocytes. In this part of the epidermis, S-100 protein-positive cells lay close together, and many stained strongly. In earlier work, large amounts of metabolic enzymes were found at the same sites in traumatized naevi and giant cells. These results suggest that a high degree of expression of S-100 protein is due to metabolic activity shown, for example, by giant naevus cells and basal melanocytes of the regenerating epidermis over traumatized naevi.

S-100 protein positive cells in nasopharyngeal carcinoma (NPC): absence of prognostic significance. A clinicopathological and immunohistochemical study of 40 cases

An immunohistochemical study of S-100 protein in 43 nasopharyngeal carcinomas (NPC) of known clinical evolution (33 primary and 10 metastatic) is presented. Sixty per cent of primary site cases as well as all metastatic forms showed S-100 protein positive cells intermingled with tumour cells. These S-100 positive elements were identified as Langerhans cells. No significant differences were found when correlating S-100 protein positivity and histological NPC variants, neither in age nor in sex of patients. Statistical analysis failed to demonstrate any positive correlation between S-100 protein reactivity and clinical survival.