Chu L, Abdul A, Takahashi T, Kojima A, Himiya T, Kusama K, Komiyama K, Hori M, Matsumoto M, Tanaka H
Department of Pathology, Nihon University School of Dentistry, Tokyo, Japan.
J Nihon Univ Sch Dent. 1993 Jun;35(2):124-9. doi: 10.2334/josnusd1959.35.124.
A case of amelanotic melanoma arising in the upper molar region, which was difficult to diagnose histologically, is reported. The patient was a 79-year-old woman, who complained of a painful swelling in the gingiva of the left upper molar region. Routine histological examination showed that the lesion was composed of diffusely scattered atypical cells with round, spindle-shaped and irregular nuclei and scanty fibrous connective tissue. A fascicular arrangement was often found in the lesion, and no cancer nests were observed. Immunohistochemical study demonstrated positive staining for S-100 protein in both the nuclei and cytoplasm of the tumor cells. Electron microscopic examination revealed that cell organelles were abundant, and an interrupted basal lamina was often found along the cell membrane. The preliminary diagnosis was a non-epithelial malignant tumor. After surgery, histological examination of metastases in lymph nodes from the submandibular region revealed that the tumor cells contained melanin pigment in the cytoplasm, as confirmed by Masson's melanin stain. The final pathological diagnosis was therefore amelanotic melanoma. Immunohistochemical staining for S-100 protein may be useful for differential diagnosis of amelanotic melanoma in conjunction with electron microscopic examination.
报告了一例发生于上颌磨牙区的无色素性黑色素瘤，其在组织学上难以诊断。患者为一名79岁女性，主诉左上磨牙区牙龈疼痛性肿胀。常规组织学检查显示，病变由散在分布的非典型细胞组成，细胞核呈圆形、梭形及不规则形，纤维结缔组织稀少。病变中常可见束状排列，未观察到癌巢。免疫组织化学研究显示肿瘤细胞核及细胞质中S-100蛋白呈阳性染色。电子显微镜检查显示细胞器丰富，细胞膜周围常可见基底膜中断。初步诊断为非上皮性恶性肿瘤。手术后，对下颌下区淋巴结转移灶的组织学检查显示，经Masson黑色素染色证实，肿瘤细胞胞质内含有黑色素。因此，最终病理诊断为无色素性黑色素瘤。S-100蛋白免疫组织化学染色结合电子显微镜检查可能有助于无色素性黑色素瘤的鉴别诊断。
