[Neurilemmoma of the soft tissues: an analysis of 1,271 tumors in an attempt at subtyping].

A total of 1,271 neurilemmoma occurring in 1,202 Japanese patients were reviewed, classifying into seven categories: ordinary (932), degenerated (238), cellular (19), plexiform (35), pigmented (2), myxomatous (16) and organoid (30) types. The present clinicopathologic study revealed that some of these types possessed distinguishing characteristics. Tumors of both degenerated and cellular types usually occurred in the deep soft tissues and were larger in size than tumors of ordinary type. Degenerated type tumors had longer duration before surgery than other type tumors in average, and one of the cellular type tumors had histologically been diagnosed as malignant. Plexiform neurilemmoma often developed in the superficial tissues, such as the skin and the subcutaneous tissue, of younger patients with longer durations and histologically exhibited intraneural growths. Organoid tumors consisting mainly of multiple complexes resembling the touch corpuscles were characterized by the younger average age of patients and by the site preference of the head and neck. A few cases of this type were connected with nerve trunks and suffered pain. Myxomatous neurilemmoma reminiscent of nerve sheath myxoma occurred in deep soft tissues of the extremities and showed a predilection for females (M:F = 4:12). Six of the seven patients with myxomatous neurilemmoma with available informations gave a distinct relation with nerve trunks and 11 of the 12 patients complained of pain. Seventy-two of the 1,202 patients had multiple neurilemmoma, in which 14 had clinically been diagnosed as von Recklinghausen's neurofibromatosis. While recurrences were evident in nine patients with neurilemmoma, including six with ordinary type tumor and three with degenerated neurilemmoma, no patients had died of the tumor.