Case of exogenous insulin-derived acanthosis nigricans caused by insulin injections.

A 73-year-old male with diabetes mellitus had been treated with insulin for six years. He developed a solid mass on his left lateral of the abdomen at the insulin injection site. A firm subcutaneous mass with dark-red erythema was overlaid by dark-brown keratinized plaques. On histological examination of the mass, keratin proliferation and epidermal papilloma were observed. There were four previously reported cases of acanthosis nigricans that were considered to be caused by continuous injections of insulin. Using immunohistochemistry, in our case the findings were positive in the basal epithelial and prickle cell layers when the patient's lesion was dyed with insulin-like growth factor (IGF)-1 antibody. The coexistence of dermal IGF-1 receptor and acanthosis nigricans found in our patient has not been reported previously, to our knowledge.

The incidence of internal malignancies in autoimmune bullous diseases.

Autoimmune bullous diseases are classified into pemphigus and pemphigoid. Pemphigus is designated as incurable disease by the Ministry of Health, Labor and Welfare, and it is said that pemphigus is difficult to care and can be fatal. The clinical course of bullous pemphigoid (BP) is better than that of pemphigus. However, as to the incidence of internal malignancies, it is well known that there is a significant difference between the two diseases. As the incidence of internal malignancies is high in BP, it is described in textbooks that patients with BP should be followed by a detailed screening for internal malignancies. We investigated the incidence of internal malignancies in 204 Japanese patients with autoimmune bullous disease who visited Tokai University Hospital in Kanagawa, Japan. We found that the incidence of internal malignancies was 11.2% in patients with pemphigus and 10.4% in patients with BP. Among pemphigus variants, the incidence was as high as 20% for pemphigus erythematosus. No relationship was found between malignancies and the severity of the autoimmune bullous diseases. Therefore it is clinically important to carry out a detailed screening for internal malignancies in patients with pemphigus as well as in patients with BP.

A case of atypical benign fibrous histiocytoma.

A case of atypical benign fibrous histiocytoma is reported. A 62-year-old Japanese female visited our clinic because of an asymptomatic solitary lesion on the skin of the left leg. Physical examination revealed a polypoid mass lesion (2.5 x 2.3 x 1.8 cm) with central erosion. The lesion began with a 1 mm-sized papule and slowly enlarged over the 20 years. Clinical diagnosis was a malignant tumor such as dermatofibrosarcoma protuberans, atypical fibroxanthoma or adnexal tumors. Biopsy of the polypoid lesion was carried out. Histopathological examination revealed a polypoid lesion consisting of proliferation of fibroblast-like spindle cells in the dermis. Large atypical cells with pleomorphic nuclei were occasionally observed but mitotic figures were rare. From immunohistochemical results (CD68, Factor-XIII, MIB-1 labeling index), we diagnosed this case as "atypical benign fibrous histiocytoma (ABFH)". Clear distinction has not been made between ABFH, a variant of benign fibrous histiocytoma, and atypical fibroxanthoma, which is a variant of malignant fibrous histiocytoma. Here we report a case of ABFH with a diagnosis of the neoplasm.