myelin-basic-protein and Nevus--Pigmented

We report a case of nevus spilus with neurotized nevus studied by immunohistochemical methods using S-100, leu-6, glial fibrillary acid protein (GFAP), and myelin basic protein (MBP). Histologic findings of the speckled lesion showed irregular rete ridge elongation, increased epidermal melanocytes and melanin in the epidermis, and scattered nevus cell nests in the upper dermis, but showed neurotized nevus in the deep dermis, which has many features of neurofibroma. Diffuse expression of S-100 protein and MBP, focal staining with GFAP, and lack of staining with leu-7 were observed, Leu-7, positive only in neurofibromas and not in neurotized nevus, appears to be the more pertinent method for distinguishing neurotized nevus from neurofibroma.

Topics: CD57 Antigens; Child; Female; Glial Fibrillary Acidic Protein; Humans; Myelin Basic Protein; Nevus, Pigmented; S100 Proteins; Skin Neoplasms; Toes

Neurofibromas are often clinically, as well as histologically, indistinguishable from completely neurotized melanocytic nevi. We tested the hypothesis that immunologic markers would differentiate the perineural fibroblasts and Schwann cells of neurofibromas from the neurotized cells of melanocytic origin. We examined eight partially neurotized acquired melanocytic nevi, three partially neurotized congenital melanocytic nevi, and five neurofibromas, with antibodies directed against S-100 protein, Leu-7(HNK-1), glial fibrillary acid protein (GFAP), and myelin-basic protein (MBP). A histologic diagnosis of neurofibroma was based on identification of a dermal proliferation of spindle-shaped cells with wavy nuclei, in a background of loose reticulated collagen. Neurotized nevi were diagnosed upon recognition of scattered nests of type A or B nevus cells, surrounded by basement membrane, present in the papillary dermis of lesions otherwise indistinguishable from neurofibromas. The congenital nevi were all large melanocytic nevi known to be present at birth. S-100 stained the majority of neoplastic cells in all neurofibromas, neurotized acquired nevi, and neurotized congenital nevi. Neurofibromas showed focal staining for Leu-7, GFAP, and MBP. In contrast, neurotized acquired and congenital nevi failed to express these markers. We believe that Leu-7, GFAP, and MBP may be helpful in differentiating neurofibromas from completely neurotized melanocytic nevi. The differences in the immunohistochemical profiles of neurofibromas and neurotized nevi support the concept that these neoplasms are histogenically distinct, despite their similar histologic appearance.

Topics: Antigens, Differentiation; Antigens, Surface; Biomarkers, Tumor; Cell Transformation, Neoplastic; Glial Fibrillary Acidic Protein; Humans; Immunohistochemistry; Killer Cells, Natural; Melanocytes; Myelin Basic Protein; Neurofibroma; Nevus, Pigmented; S100 Proteins; Skin Neoplasms; Staining and Labeling

The presence of myelin basic protein (MBP) within a skin neoplasm would support its derivation from Schwann's cells, since this substance is routinely present within Schwann's cells in the peripheral nervous system. Using a monoclonal antibody prepared against MBP and an unlabeled antibody peroxidase-antiperoxidase assay, we surveyed a variety of skin lesions suspected of being derived from Schwann's cells to determine whether MBP was present. Myelin basic protein was detected within the cytoplasm of cells composing benign solitary schwannoma (neurilemmoma) and neurofibroma, confirming the association of these lesions with proliferation of Schwann's cells. Myelin basic protein was not found in a variety of intradermal and compound nevus cell nevi nor in malignant melanoma. This negative finding supports electron microscopic evidence suggesting that nevus cells have no relationship to Schwann's cells even though some nevus cell arrangements suggest Schwann's cell derivation under the light microscope.

Topics: Animals; Antibodies, Monoclonal; Histocytochemistry; Humans; Immunoenzyme Techniques; Melanoma; Mice; Mice, Inbred BALB C; Myelin Basic Protein; Neurilemmoma; Neurofibroma; Nevus, Pigmented; Skin Neoplasms; Swine