Rare case of composite embryonal rhabdomyosarcoma and leiomyosarcoma of the tongue of an adult

The differential diagnosis of embryonal rhabdomyosarcoma (RMS), pleomorphic sarcoma, and leiomyosarcoma remains a challenge because of their overlapping histological presentations, with serious implications on the choice of treatment. We report a rare case of a tumor confined to the tongue in a 22-year-old woman. Clinical, histological, and immunohistochemical data confirmed the diagnosis of a composite tumor of embryonal RMS and leiomyosarcoma based on the presence of spindle-shaped cells within a myxoid background of spherical cells and immunoreactivity to muscle-specific markers (desmin, smooth-muscle actin, muscle-specific actin, myoglobin, and vimentin), RMS-specific myogenin, and leiomyosarcoma-specific h-caldesmon. The lack of immunoreactivity to S-100 and cytokeratin antibodies suggested the absence of melanoma and pleomorphic sarcoma, respectively. Presurgical treatment with a single round of broad-spectrum MAID (mesna, pirarubicin, ifosfamide, and dacarbazine) adjuvant therapy for the advanced soft tissue sarcoma allowed the growth of the tumor from 45 mm × 38 mm × 25 mm to 45 mm × 40 mm × 40 mm. Thereafter, subtotal glossectomy was performed. Based on the strong immunoreactivity of the tumor to myogenin, the patient received RMS-specific VAC (vincristine, actinomycin D, and cyclophosphamide) chemotherapy over 6 months. However, metastases to the lungs led to the patient's death. This case highlights the danger of “overdiagnosing” a patient, and the need to select a broad-spectrum adjuvant whenever a diagnosis of composite sarcoma is suspected.