Differentiated rhabdomyomatous tumors after chemotherapy for metastatic testicular germ-cell tumors: a clinicopathological study of seven cases mandating separation from rhabdomyosarcoma

Abstract

To gain insight concerning prognosis, we investigated seven cases of post-chemotherapy retroperitoneal lymph-node dissections from patients with testicular germ-cell tumors that contained sizable nodules of differentiated skeletal muscle, but that lacked both a primitive cellular component and mitotic activity. The patients were 18-28 years old at the time of retroperitoneal lymph-node dissection. All had a previous nonseminomatous germ-cell tumor of the testis, five of which had a teratoma component. In one the testicular tumor had foci of embryonal rhabdomyosarcoma. The retroperitoneal lymph-node dissections were performed 0.2-4.7 years after orchiectomy, all following cisplatin-based chemotherapy, and contained rhabdomyomatous tumors that ranged from 0.8-5 cm. These consisted of nodular to diffuse aggregates of fetal-type rhabdomyocytes with central to peripheral nuclei and abundant, eosinophilic, fibrillary cytoplasm with occasional cross striations. Elongated myotubes with multiple nuclei in a common sarcoplasm occurred at least focally in all cases. Mild to moderate nuclear atypia, including nuclear enlargement and nucleolar prominence, was present, but mitotic activity, necrosis, and a primitive cellular component were absent. All but one retroperitoneal lymph-node dissection also contained other teratomatous elements. Follow-up in six patients showed three were disease free at 2.2-3.4 years; two developed recurrent teratoma at 1.3-3.7 years; and a sixth developed recurrent teratoma at 0.5 and 2 years, followed at 17 years by progressive tumor with elevated a-fetoprotein. No patient with available follow-up developed progressive sarcoma. We conclude that rhabdomyomatous tumors in retroperitoneal lymph-node dissection specimens after chemotherapy for metastatic testicular germ-cell tumors show clinical behavior similar to teratoma rather than rhabdomyosarcoma. We believe the most likely explanation for the finding of pure rhabdomyomatous tumors in this setting, a phenomenon sometimes termed 'cytodifferentiation,' is selective persistence of differentiated tumor cells because of chemotherapy. Keywords: testicular germ-cell tumor; rhabdomyomatous tumor; rhabdomyosarcoma; teratoma; retroperitoneum Sarcoma is an uncommon finding in post-chemotherapy retroperitoneal lymph-node dissection specimens and carries a poor prognosis, 1-3 with rhabdomyosarcoma being the most common form of sarcomatous transformation and usually behaving aggressively. [2][3][4] Rarely, sizable nodules of differentiated skeletal muscle are found, and it is presently unclear if these rhabdomyomatous tumors behave as teratoma or sarcoma. In this study, we report our experience with seven cases of rhabdomyomatous tumors in post-chemotherapy retroperitoneal lymph-node dissection specimens from patients with metastatic testicular germ-cell tumors to gain

A pelvic mass 21 years after a Wilms tumour: late recurrence or new tumour?

“…Previous experiences have highlighted cases of late WT recurrences with rabdomyosarcomatous differentiation, a fact that seems to indicate that treatment of the primary WT, designed to eradicate blastemic cells, could induce maturation of cancer cells along the epithelial and mesenchymal lines. 5 Anderson et al 6 found rhabdomyomatous differentiation after chemotherapy in 61% of surgical specimens in bilateral WT suggesting that chemotherapy may play a role in promoting myogenic differentiation of immature Wilms tumour components. Our pathological diagnosis, however, pointed to a prostatic embryonal rhabdomyosarcoma (PER), not correlated with the WT.…”

Testicular Germ Cell Tumors

“…12, correspond to aggregates of benign terminally differentiated rhabdomyoblasts, in the setting of teratomatous elements, and found in post-chemotherapy RPLND specimens [299]. Its recognition is important to differentiate it from rhabdomyosarcoma arising in teratoma as a somatic-type malignancy.…”

Perspectives on testicular germ cell neoplasms

“…Differentiated rhabdomyomatous tumor (Fig. 7F) may occur after chemotherapy for metastatic GCT and should be distinguished from rhabdomyosarcoma [53]. It should be considered a special form of teratoma and has a prognosis similar to that of teratoma.…”