Primary mucinous carcinoma of the scalp.

Primary cutaneous mucinous carcinoma (MC) is a rare epithelial neoplasm derived from the sweat glands. Herein, we report a case of MC located on the head. A 66-year-old woman underwent excision of a nodular tumor with a reddish brown surface on the left parietal region. Histopathology revealed a neoplasm extending from the reticular dermis into the subcutaneous fat. The tumor cell aggregates showed cribriform and solid lobules and were embedded in lakes of mucin, separated by thin, fibrous septae. Focally single neoplastic cells were arranged in an Indian-file pattern. The tumor cells displayed an eosinophilic cytoplasm, large basophilic nuclei and some discrete nuclear atypia. Vascular spaces, filled by densely packed erythrocytes between the septae, were also observed. We compared the mucinous component with the tumor cell and the stromal component by light microscopy. Analyzing the tumor by an image analysis system in Alcian-blue-stained serial sections, we found the averaged total tumor area measuring 99.7 mm(2). The area of the mucinous component measured 92.4 mm(2), that of the tumor cells 3.7 mm(2) and that of the stromal component 3.6 mm(2). The extensive checkup of the patient disclosed no evidence for a further malignant neoplasm. After excision of the tumor an adjuvant radiotherapy was performed. The patient was free of recurrence and metastatic spread of the mucinous carcinoma during a 4-year follow-up.