Cervical adult rhabdomyoma presenting as a rapidly growing mass in a patient with diffuse large B-cell non-Hodgkin's lymphoma.

BACKGROUND: Adult rhabdomyoma is a rare mesenchymal tumor, which generally grows slowly and is mainly localized in the head and neck area.

PATIENT AND METHODS: We report the extraordinary case of a rapidly growing adult rhabdomyoma in a 73-year-old man. The patient was treated for diffuse large B-cell non-Hodgkin's lymphoma with CHOP therapy (doxorubicin, cyclophosphamide, vincristine, and prednisone). Comparison of the respective computed tomography scans showed prominent enlargement of 35% in the tumor mass volume on the right side of the neck within 3 months. The tumor was highly suspicious for lymphoma. Surgical resection was performed.

RESULTS: Histological examination revealed a tumor which was composed of tightly packed polygonal cells with a PAS-positive granular or vacuolated cytoplasm, occasionally with cross-striations. Immunohistochemically, the cells were positive for desmin, myogenin, Myo-D1, but negative for S-100. Due to these characteristic morphologies, adult rhabdomyoma was diagnosed.

CONCLUSION: This is the first report on an adult rhabdomyoma with a proven rapid enlargement. The possible pathomechanisms are discussed.