Seminoma and sarcoidosis – complication of treatment response evaluation with ¹⁸F-FDG PET/CT – case report

Overview

Introduction:
¹⁸F-FDG PET/CT is a part of initial diagnosis and follow-up of the treatment response in patients with seminoma. Spread of the seminoma except of regional paraaortal lymph nodes is most frequently into the lungs, mediastinal and supraclavicular lymph nodes; less frequently into other organs (liver, brain). Coincidence with sarcoidosis is usually mentioned as a complication of diagnosis and follow-up.

Case report:
We describe two patients with testicular tumor, typical seminoma, pT1, with normal level of tumor markers. Both had intensive accumulation of ¹⁸F-FDG in the mediastinal and hilar lymph nodes without involvement of retroperitoneum. Histological verification was not recommended in the first patient (42 y/o); he underwent oncological chemotherapy with partial effect after the first line but with progression after the second line. Mediastinoscopy with histology confirmed sarcoidosis. Initial histological verification from mediastinum was performed in the second patient (45 y/o); sarcoid granulomatosis was confirmed. Pathological foci in retroperitoneum, pelvis and spine were detected on follow-up ¹⁸F-FDG PET/CT. It was considered as a progression of sarcoidosis, progression of seminoma was less probable.

Conclusion:
It is necessary to take into account also other causes of the pathological pattern of tumor spread if it is not very typical. Sarcoidosis coincides quite frequently also with lung cancers or lymphomas. Histological verification is essential in such cases.

Key Words:
seminoma, sarcoidosis, fluorodeoxyglucose, PET/CT