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

Prokopios P Argyris; Bindu Challa; Swati Satturwar; Kyle K VanKoevering; Paul E Wakely Jr

doi:10.1007/s12105-023-01610-5

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

Head Neck Pathol. 2024 Jan 18;18(1):1. doi: 10.1007/s12105-023-01610-5.

Authors

Prokopios P Argyris¹, Bindu Challa², Swati Satturwar², Kyle K VanKoevering³, Paul E Wakely Jr²

Affiliations

¹ Division of Oral and Maxillofacial Pathology, The Ohio State University College of Dentistry, Postle Hall, Room 2191 305 W. 12th Ave, Columbus, OH, 43210, USA. argyris.2@osu.edu.
² Department of Pathology, The Ohio State University Wexner Medical Center, James Cancer Hospital and Solove Research Institute, Columbus, OH, USA.
³ Department of Otolaryngology-Head and Neck Surgery, The Ohio-State University Wexner Medical Center, Columbus, OH, USA.

Abstract

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.

Keywords: Chondrosarcoma; Head and neck; IDH1/2; Isochromosome 12p; SMARCB1; Seminoma; Somatic-type malignancy; Testicular germ cell tumor.

Publication types

Case Reports

MeSH terms

Adult
Bone Neoplasms* / genetics
Chondrosarcoma* / genetics
Humans
Lymphadenopathy*
Male
Neoplasms, Germ Cell and Embryonal*
Neoplasms, Second Primary*
SMARCB1 Protein
Seminoma*
Skull Base
Testicular Neoplasms* / genetics

Substances

SMARCB1 protein, human
SMARCB1 Protein

Supplementary concepts

Testicular Germ Cell Tumor