Malignant peripheral nerve sheath tumors (MPNSTs) are defined as malignant tumors arising from peripheral nerves or differentiating along the line of the elements of the nerve sheath. MPNSTs that originate from the brain parenchyma are exceptionally rare and are termed malignant intracerebral nerve sheath tumors. We experienced a case of the epithelioid variant of malignant intracerebral nerve sheath tumor (MINST) occurring in the right frontal lobe of a 50-year-old man. He underwent gross total resection of the tumor. Histologically, the tumor cells had round, polygonal, or ovoid nuclei and moderate amounts of eosinophilic cytoplasm, which was defined as epithelioid cells. The tumor cells were arranged in short cords or nests with vaguely nodular patterns embedded in the myxoid stroma. Regarding mitotic activity, 15 mitotic figures were noted per 10 high-power fields. Immunohistochemically, tumor cells were positive for S-100 protein and synaptophysin, but negative for glial fibrillary acidic protein, HMB-45, EMA, and AE1/ AE3. Furthermore, immunostaining for INI1 was negative. Loss of the tumor-suppressor gene product SMARCB1/ INI1 expression has been recognized in epithelioid MPNST, but not in conventional MPNST. Postoperatively, he underwent radiotherapy and was followed for almost 1 year without recurrence. The present case is the first report of the epithelioid MINST.

Localized tenosynovial giant cell tumor (TGCT) usually occurs in the hand and foot regions. However, localized TGCT with extensive cartilaginous metaplasia is rare, especially in the tendon sheath of the toe. Here, we report a case of localized TGCT with cartilaginous metaplasia in a 57-year-old man. The tumor presented as a lobular mass measuring 2.2 cm in its greatest dimension and arose in the flexor digitorum tendon sheath of the right 2nd toe. Clinically, the mass was palpable 1 year ago and brought pain during walking. Microscopically, the mass was composed of focal conventional TGCT and cartilaginous components. The conventional TGCT areas consisted of mononuclear cells, multinucleated giant cells, and hemosiderin deposition. The chondroid areas were extensive and comprised more than 90% of the whole tumor. In this case, the mononuclear cells in the conventional TGCT areas showed focal immunohistochemical staining for podoplanin and S100 protein as well as diffuse staining for CD68, which is consistent with the staining pattern of conventional TGCT. The mononuclear cells in the chondroid areas were focal positive for podoplanin and diffuse positive for S100 protein. Chondroid metaplasia in diffuse TGCT has been reported in 10 cases involving the temporomandibular, elbow, and hip joints. However, there has been no report of a localized form of chondroid TGCT involving an extra-articular region.

The previous studies of p16^INK4a, pRb, p53, and Ki-67 expression suggested that these markers may be preferentially expressed in cervical neoplasms. The purpose of this study was to assess the expression and the clinical significance of p16^INK4a, pRb, p53, and Ki-67 proteins in cervical lesions. We obtained 106 cases with various categories of cervical squamous mucosa, including squamous cell carcinoma (n=35), cervical intraepithelial neoplasia (CIN) II/III (n=26), CIN I (n=10), squamous metaplasia (n=15), and normal squamous mucosa (n=20). Immunohistochemical staining was performed for p16INK4a, pRb, p53, and Ki-67 proteins in formalin-fixed and paraffin-embedded tissue sections of the uterine cervix. Evaluation of immunohistochemical staining was based on the frequencies of expression and the mean immunoreactivity scores (IS) in each diagnostic category. p16INK4a positive sotaining was observed in 26 of 35 cases (74.3%) of squamous cell carcinoma, in 16 of 26 cases (61.5%) of CIN II/III, in six of 10 cases (60%) of CIN I, in nine of 15 cases (60%) of squamous metaplasia, and negative in normal squamous mucosa. pRb expression was detected in all diagnostic categories; however, the proportion of pRb positive cells was relatively decreased in CIN II/III (38.5%) and squamous cell carcinomas (51.4%), compared to normal squamous epithelium (90%) and squamous metaplasia (73.3%). No significant differences in expression of p53 were observed in any diagnostic categories. Ki-67 expression was increased in squamous cell carcinoma (37.1%), CIN II/ III (42.3%), and CIN I (40%), but negative in squamous metaplasia and normal mucosa. In 35 cases of squamous cell carcinomas, multivariate analysis revealed no differences in p^INK4a, pRb, p53, and Ki-67 expression according to the age of the patient, lymph node metastasis and clinical stage. In conclusion, the combined use of p16^INK4a and Ki-67 immunoreactivity could improve the diagnostic specificity of squamous cell carcinoma of the uterine cervix.

Malignant transformation of mature cystic teratoma (MCT) is rare. Sarcomatoid carcinoma is a neoplasm comprising malignant mesenchymal cells and a conventional carcinomatous area. Here, we report on a case of sarcomatoid carcinoma arising from an MCT in the left ovary of a 45-year-old female. A unilocular cyst consistent with MCT was observed; however, a nodule within the cyst was confirmed from the resected ovary. Microscopically, the nodule showed both squamous cell carcinoma and pleomorphic sarcomatous components admixing with each other. Lining epithelial cells at the periphery of the main tumor showed squamous metaplasia. When a sarcomatous component is observed in the ovary tumor, it is important to find a squamous cell component, either benign or malignant.