mart-1-antigen and Nerve-Sheath-Neoplasms

Four cases of a rare melanotic variant of malignant nerve sheath tumour (MNST) in dogs are described. All four cases presented with neurological clinical signs due to multicentric, intradural, intra- and extraparenchymal neoplasms that surrounded the spinal and cranial nerves and infiltrated the adjacent spinal cord and brain. The dogs were young (3 months to 3 years of age), all were female and four different breeds were represented. Characteristic histological features were interweaving fascicles of spindle-shaped cells, sometimes with an architecture reminiscent of Antoni A and B patterns. Some spindle cells showed prominent cytoplasmic melanin pigmentation and such cells were positive by Masson-Fontana stain. Immunohistochemistry performed in three cases was positive for S100 and vimentin, strongly positive for melan A in the melanized cells and negative for glial fibrillary acidic protein and periaxin. Non-melanized cells did not express melan A. Transmission electron microscopy findings in one case were consistent with a peripheral nerve sheath tumour and demonstrated cytoplasmic pre-melanosomes and melanosomes. Melanotic variants of MNSTs are rare in animals with only a solitary report of two previous canine cases in the literature.

Topics: Animals; Dog Diseases; Dogs; Female; Immunohistochemistry; MART-1 Antigen; Microscopy, Electron; Nerve Sheath Neoplasms; Peripheral Nerves; Peripheral Nervous System Neoplasms; Spinal Cord; Vimentin

Neural differentiation by melanocytic nevi represents a well-recognized phenomenon, and melanocytic nevi with perineurial differentiation have been reported recently. We reported a case of a congenital melanocytic nevus with histopathologic features of hybrid schwannoma/perineurioma. The patient was a 36-year-old male who presented with a black tumor on his arm since birth. Histopathology showed a congenital melanocytic nevus in the superficial dermis, but more strikingly, in continuity with the melanocytic nevus, there was a well-circumscribed but unencapsulated nodule in the deep dermis. The nodule was composed of cellular and myxoid areas with storiform, laminated or whorled growth patterns. The cellular area was mainly composed of proliferation of plump spindle, oval or epithelioid cells. The myxoid area was mainly composed of proliferation of slender spindle cells with mucin deposition. Immunohistochemical stains showed that the cellular area was positive for S100 and CD34, weakly positive for EMA, negative for Glut-1 and collagen IV, the myxoid area was positive for S100, negative for CD34, strongly positive for EMA and focally positive for Glut-1 and collagen IV. Our results show that congenital melanocytic nevi may show neural differentiation with histopathologic features of hybrid schwannoma/perineurioma.

Topics: Adult; Biomarkers, Tumor; Humans; Male; MART-1 Antigen; Neoplasms, Multiple Primary; Nerve Sheath Neoplasms; Neurilemmoma; Nevus, Pigmented; S100 Proteins; Skin Neoplasms

Myxoid variant of adrenocortical carcinomas (ACC) are rare, there being only 11 cases in the literature to date. Reported herein are the findings of a case, which in contrast to all previously reported myxoid ACC, was devoid of typical non-myxoid areas. The patient was a 61-year-old man in whom a left adrenal mass was detected during investigation of Cushing's syndrome. The adrenal was replaced by malignant cells and expanses of myxoid material. The cells were positive for melan-A, synaptophysin, vimentin and alpha-inhibin. The ultrastructural features of the cells were typical of adrenal cortical differentiation. The differential diagnosis of myxoid ACC includes extraskeletal myxoid chondrosarcoma, chordoma, myxoid adenocarcinoma, myxoma, lipomatous tumors, nerve sheath tumors, smooth muscle tumors, gastrointestinal stromal tumor and other sarcomas. The presence of myxoid material in a retroperitoneal lesion raises a broad differential diagnosis in which myxoid adrenocortical neoplasms should be included. Clinicoradiological correlation may be helpful, but special stains, immunohistochemistry and ultrastructural examination may be necessary to establish the diagnosis.

Topics: Adenocarcinoma; Adrenal Cortex Neoplasms; Adrenocortical Carcinoma; Antigens, Neoplasm; Chordoma; Diagnosis, Differential; Humans; Immunohistochemistry; Male; MART-1 Antigen; Microscopy, Electron; Middle Aged; Myxoma; Neoplasm Proteins; Nerve Sheath Neoplasms; Retroperitoneal Neoplasms; Synaptophysin; Vimentin

The diagnosis of malignant melanoma remains one of the most difficult to render in surgical pathology, partially because of its extreme histologic variability. Limits in the sensitivity and/or specificity of the currently available melanocytic markers such as anti-S100, HMB45, and anti-MelanA further complicate this problem. Previous work has demonstrated that the B-cell proliferation/differentiation marker MUM1/IRF4 is detected in malignant melanoma and hematolymphoid malignancies, but not in any other neoplasm tested (including colonic, lung, breast, and ovarian carcinomas). In the current study, we have examined MUM1 protein expression in 61 melanocytic lesions and compared the diagnostic usefulness of this marker with that of anti-S100, HMB45, and anti-MelanA. The results indicate that MUM1 is positive in 33/36 (92%) cases of melanoma (21/22 [95%] conventional primary melanomas and 12/14 [86%] metastatic melanomas). In comparison, positivity was seen with anti-S100 in 36/36 cases (100%, 22 primary and 14 metastatic), HMB45 in 28 cases (78%, 17 primary and 11 metastatic), and anti-MelanA in 27 cases (75%, 19 primary and 8 metastatic). Although negative in schwannomas, neurofibromas, and malignant peripheral nerve sheath tumors, MUM1 is detected in only one in eight cases of spindle cell and desmoplastic melanomas. With the exception of desmoplastic and spindle cell melanomas, MUM1 appears to be a sensitive and specific immunohistochemical stain for melanocytic lesions and may prove to be a useful addition to the current panel of melanoma markers.

Topics: Antigens, Neoplasm; B-Lymphocytes; Biomarkers, Tumor; Diagnosis, Differential; DNA-Binding Proteins; gp100 Melanoma Antigen; Humans; Immunohistochemistry; Interferon Regulatory Factors; MART-1 Antigen; Melanoma; Membrane Glycoproteins; Neoplasm Proteins; Nerve Sheath Neoplasms; Nevus; S100 Proteins; Transcription Factors

Topics: Antigens, Neoplasm; Biomarkers, Tumor; Cartilage; Diagnosis, Differential; Epithelioid Cells; Humans; MART-1 Antigen; Melanoma-Specific Antigens; Melanoma, Amelanotic; Neoplasm Proteins; Nerve Sheath Neoplasms; Neurilemmoma; Soft Tissue Neoplasms

A majority of desmoplastic melanomas and some of the other forms of melanomas are S-100 positive and HMB45 negative; this pattern of immunoreactivity is similar to certain nerve-derived tumors such as malignant peripheral nerve sheath tumor. In this study the immunostaining profile of HMB45-negative malignant melanomas was evaluated by a panel of antibodies against markers associated with melanoma and melanocytic differentiation, including microphthalmia transcription factor, tyrosinase, Melan-A, and MAGE-1. Immunodetection was performed on paraffin sections of 22 cases of HMB45-negative malignant melanomas (including 8 spindle cell melanomas, 8 desmoplastic melanomas, and 6 epithelioid melanomas), 8 HMB45-and S-100-positive malignant melanomas, 15 malignant peripheral nerve sheath tumors, 16 schwannomas, and 11 neurofibromas. Of eight HMB45-positive malignant melanomas, all were positive for Melan-A, tyrosinase, and melanocyte-specific transcription factor, and three were positive for MAGE-1. In the 14 HMB-45 negative, nondesmoplastic melanomas, melanocyte-specific transcription factor was positive in 9, Melan-A in 9, tyrosinase in 6, and MAGE-1 in 11. In eight desmoplastic malignant melanomas, MAGE-1 was positive in three, and all other markers were negative. The five markers tested were negative in all but two schwannomas, one with focal melanocyte-specific transcription factor and the other with tyrosinase and weak MAGE-1 reactivity. MAGE-1, melanocyte-specific transcription factor, tyrosinase, and Melan-A are useful markers in the diagnosis of malignant melanocytic lesions when HMB45 is negative. MAGE-1 may be useful in differentiating melanocytic lesions from nerve-derived lesions, but its sensitivity is relatively low. The immunostaining profile of desmoplastic malignant melanomas more closely resembles that of malignant peripheral nerve sheath tumor than that of other types of malignant melanoma. Melanocyte-specific transcription factor is not a useful marker for desmoplastic melanoma.

Topics: Antigens, Neoplasm; Biomarkers, Tumor; DNA-Binding Proteins; Humans; Immunophenotyping; MART-1 Antigen; Melanoma; Melanoma-Specific Antigens; Microphthalmia-Associated Transcription Factor; Monophenol Monooxygenase; Neoplasm Proteins; Nerve Sheath Neoplasms; Peripheral Nervous System Neoplasms; S100 Proteins; Transcription Factors