Primary Cutaneous Signet-Ring Cell Melanoma

Abstract

Signet-ring cell malignant melanoma is a rare histopathologic variant of malignant melanoma with only a few described cases. We report the clinical, histopathological, and immunohistochemical features of two cases of primary cutaneous signet-ring cell malignant melanoma. Neoplastic melanocytes showed abundant clear cytoplasm compressing the nuclei to the periphery, sometimes resulting in a signet-ring appearance. Immunohistochemically, neoplastic melanocytes in both cases expressed immunoreactivity for the usual melanocytic markers S-100 protein and Melan-A, although only the second case resulted HMB-45 positive. We review the literature about this rare cytologic variant of malignant melanoma and discuss the differential diagnosis with other cutaneous neoplasms that may show a signet-ring cell appearance of their neoplastic cells.

Signet-ring cell melanoma with sentinel lymph node metastasis: A case report with immunohistochemical analysis and review of the clinicopathological features

“…This disease commonly affects middle-aged males (average age of 57.8-years and male/female ratio of 14:7), however, young individuals may also be affected (range, 18–85-years-old). Metastatic signet-ring cell melanoma in a patient with an unknown primary tumor has been documented (2) and six cases, including the present case, exhibited no primary sites (Table I). The present case exhibited no in situ component in the overlying epidermis and the patient had no past history of malignant melanoma and tumorous lesions with the exception of the tumor in the thigh, therefore, the cutaneous lesion may not be confirmed as the primary lesion.…”

“…Ultrastructural examination revealed that this characteristic morphology in signet-ring cell melanoma is often imparted by the intracytoplasmic accumulation of intermediate filaments, particularly vimentin (2). This observation corroborates the immunohistochemical results of the present case report since vimentin was found to be expressed in the cytoplasm of the signet-ring cells, although, ultrastructural examination was not performed.…”

“…This type of tumor usually shows positive immunoreactivity for melanocytic markers, including S-100 protein, Melan-A and HMB-45. However, it is important to recognize that exceptions to this phenotype exist as S-100 protein-negative (1/20 cases) or HMB-45-negative cases (4/21 cases) have been documented (Table I) (2,4). Therefore, a combination of these markers is useful for establishing a diagnosis.…”

“…Signet-ring cell melanoma is one of the rarest histopathological variants of malignant melanoma, characterized histopathologically by the presence of tumor cells in which the nucleus is compressed to the cellular periphery, appearing as signet-rings (2). This variant was initially described by Sheibani and Battifora in 1988 (3) and since then, 20 cases have been reported in English literature (2–15).…”

“…Signet-ring cell melanoma is one of the rarest histopathological variants of malignant melanoma, characterized histopathologically by the presence of tumor cells in which the nucleus is compressed to the cellular periphery, appearing as signet-rings (2). This variant was initially described by Sheibani and Battifora in 1988 (3) and since then, 20 cases have been reported in English literature (2–15). The current case report presents an additional case of signet-ring cell melanoma with sentinel lymph node metastasis, analyses of the immunohistochemical expression profiles of the intermediate filaments and mammalian target of rapamycin (mTOR) pathway proteins and review of the clinicopathological features of this extremely rare variant of malignant melanoma.…”