Benign symmetrical lipomatosis is a rare condition in Japan. It is characterized by diffuse and symmetrical deposition of adipose tissue on the neck, back and upper trunk.
A 38-year-old man was seen at the hospital because of painless lesions in the anterior thoracic region, clavicular areas and back. CT of the neck revealed development of fibrous adipose tumors, which did not oppress nor invade the neighboring structures. After admission, the pathological report from surgical biopsy under local anesthesia described the specimens as “normal adult adipose tissue”. Resection of the adipose tissue was performed under general anesthesia. At laparotomy, adipose tumors with unclear border were observed invading under the bilateral trapezius muscles and around the calvicular areas. Total tissue removed from the left-lateral surgical wound was 190 g in weight, and 160 g from the right-lateral wound. Histopathological findings included a small percentage of immature adipose cells with glycogen in their nuclei scattered among mature adipose cells. This case is discussed with a review of the literature.