Pure Testicular Seminoma Relapsing Late with Somatic Type Malignancy

SMARCB1-Deficient Skull Base Chondrosarcoma with 12p Duplication Presenting as Somatic-Type Malignancy Arising from Metastatic Seminoma

Somatic-type malignancy (STM) can occur infrequently within a primary or metastatic testicular germ cell tumor (TGCT) and is associated with dismal prognosis and survival. STM with chondrosarcomatous features is exceedingly rare and head and neck involvement has not been previously documented. A 39-year-old white man presented with nasal obstruction and epistaxis. Imaging disclosed a 6.9-cm expansile tumor involving the nasal cavity and skull base with intraorbital and intracranial extension. The histopathologic properties of the tumor were compatible with chondrosarcoma, grade II-III. Immunohistochemically, malignant cells were strongly and diffusely positive for S100 and epithelial markers, and showed loss of SMARCB1 expression. IDH1/2 mutations were not detected. Following whole-body PET scan, a 7.0-cm left testicular mass was discovered and diagnosed as seminoma with syncytiotrophoblastic cells, stage pT3NXM1b. Extensive retroperitoneal, mediastinal, and supraclavicular lymphadenopathy was also noticed. Histopathologic examination of the left supraclavicular lymph node revealed metastatic seminoma. By FISH, most metastatic nodal seminoma cells harbored 1 to 4 copies of isochromosome 12p, while the chondrosarcoma featured duplication of 12p. Presence of a malignant TGCT with disseminated supradiaphragmatic lymphadenopathy, the unique immunophenotypic properties of the skull-based chondrosarcoma and lack of IDH1/2 aberrations with gain of 12p strongly support the diagnosis of STM chondrosarcoma arising from metastatic TGCT. The patient did not respond to chemotherapy and succumbed three months after diagnosis. Although exceedingly uncommon, metastasis to the head and neck may occur in patients with TGCT. This case of STM chondrosarcoma demonstrated divergent immunophenotypic and molecular characteristics compared to "typical" examples of head and neck chondrosarcoma. High index of suspicion is advised regarding the diagnosis of lesions that present with otherwise typical histomorphology but unexpected immunohistochemical or molecular features.

Two cases of somatic-type malignancy as a very late relapse of testicular cancer successfully managed by surgical resection

A late-relapse germ cell tumor might contain malignant non-germ cell tumors, known as 'somatic-type malignancy (SM)'. The development of a secondary SM is rare, and this phenomenon remains poorly understood. Case 1 developed lung metastasis 13 years after chemotherapy followed by retroperitoneal lymph node dissection for stage IIA non-seminoma. The tumor increased in size after chemotherapy. The patient underwent a pneumonectomy. Pathology revealed an adenocarcinoma with immature teratoma. The patient has experienced no relapse for 9 years. Case 2 developed a pelvic tumor after 10 years of surveillance for stage I seminoma. The tumor increased in size after chemotherapy. The patient underwent pelvic tumor resection with cystectomy. Pathology revealed a mature teratoma with SMs consisting of sarcoma and adenocarcinoma. The patient has experienced no relapse for 6 months. Surgical resection played a major role in the treatment of very late-relapse germ cell tumors with SM.