Giant annular dermatomyofibroma

A 74-year-old lady presented with a painful giant annular abdominal plaque for a duration of 2 years. The plaque developed from a cholecystectomy scar and extended peripherally around it. The patient had had a cholecystectom y for gallstones 10 years previously. She was a diabetic on oral hypoglycaemic agents and had no history of radiotherapy. Physical examination showed a tender well-demarcated annular erythematous keloid-like plaque, measuring 13 cm x 15 cm, surrounding a cholecystectomy scar. Another smaller oval plaque, measuring 3 cm x 2 cm, was found on the left side of the abdomen (Fig. 1). The initial clinical diagnosis was dermatofibrosarcoma protuberan (DFSP). A deep incisional biopsy including subcutaneous fat was performed under local anesthesia for pathological examination. Histologically, there was a plaque-like lesion involving the upper reticular dermis but not extending to the subcutaneous fat. The lesion showed proliferation of spindle-shaped cells arranged in intersecting fascicles and appeared parallel to the skin surface. Only a vague storiform pattern was seen at the edges. The cells had relatively uniform elongated nuclei and mitosis was not seen. The overlying epidermis showed mild hyperplasia with pigmentation of the basal layer (Fig. 2). Smooth muscle actin was positive (Fig. 3), desmin was negative and CD34 was negative. The final diagnosis was dermatomyofibroma (DMF). Extra-abdominal fibromatosis was unlikely because broad elongated fascicles among collagenous stroma were not evident, while intersecting fascicles parallel to the skin surface were typical of DMF The smaller plaque on her left abdomen was excised and gave similar histological and staining results. The giant annular plaque was not excised as the patient refused further surgery. She has since been closely monitored.