Calcified embryonal rhabdomyosarcoma with local bone invasion. An unusal case.

Abstract

Rhabdomyosarcoma is a relatively uncommon tumor (1–12) of skeletal muscle, in which the incidence of radiographically detectable calcium is exceedingly rare. The presence of calcium noted on the roentgenograms in the soft-tissue mass associated with this tumor prompted us to document the case reported here. Despite its presumably infrequent occurrence, rhabdomyosarcoma was the third most common tumor of childhood in a series of 310 solid tumors reviewed by Bailey et al. (2), exceeded only by Wilms's tumor and neuroblastoma. The neoplasm may be classified as follows: (a) pleomorphic rhabdomyosarcoma (2); (b) embryonal rhabdomyosarcoma (2), alveolar rhabdomyosarcoma (2); and (c) a botryoid variant (7, 9), which is accepted by some authors as an embryonal lesion (10) and by others as a teratoma (8). Of these variants, the embryonal lesion has come to be recognized, within the past decade, as the most common skeletal muscle tumor (9). It affects children more frequently than adults and is found in the head, neck, pelvic organs, and extremities (6, 9). Lawrence et al. (6) in reviewing 48 cases of embryonal sarcoma from which they excluded lesions of the head and neck and genitourinary tract, found the extremities and abdomino-retroperitoneal areas to be the most frequent sites of this disease. The neoplasm, in females, exhibited a predilection for the extremities and, in men, was frequently in the retroperitoneal region. Pathologically, rhabdomyosarcomas are said to recapitulate the process of normal skeletal muscle development, but in a highly disorganized manner (10). It is not uncommon for a pseudocapsule to be present, which allows apparent complete stripping of the tumor from its surrounding bed. Unfortunately, no true capsule exists. Large areas of hemorrhage and necrosis are common within the tumor bulk. In the literature reviewed, the only mention made of calcium in these lesions (outside of the bladder) was by Albores-Saavedra (1) who described two cases (out of a total of 35) of alveolar rhabdomyosarcoma in which the soft-tissue masses contained calcified spots “as in chondrosarcoma and synovial sarcoma.” These two cases are of further interest, in view of our present case, in that one was found in the scapular region and one in the thigh. Both invaded bone directly. This invasive behavior is somewhat unusual for embryonal lesions. As Caffey (4) pointed out, metastasis to the skeleton is not uncommon and mimics neuroblastoma, but direct extension to bone was not seen in his cases. Other authors likewise point out the rarity of direct bony extension (5). Linscheid et al. (7), however, in their review of pleomorphic rhabdomyosarcoma, point out that bone involvement was noted in eight instances and was located, most frequently, about the shoulder and sacrum. Metastasis to the skeleton occurred in only three cases. Case Report A 3-year-old girl was admitted to the hospital on April 9, 1966. Three days before, her mother noted a lump on the right scapula while bathing the child.