Granulomatous reaction of primary mediastinal seminoma leading to diagnostic delay: a case report

Abstract

Primary mediastinal seminoma (PMS) is a rare tumor. PMS can be morphologically related to secondary changes in the form of thymic remnants, cystic degeneration, epithelioid granulomas, fibrotic change, and syncytiotrophoblast-like cells. Ours was an interesting case where a 26-year-old male presented with an incidentally-found anterior mediastinal mass. Even though he had no pulmonary symptoms, the transthoracic co-axial needle biopsy of the mass suggested tuberculosis (TB). However, on follow-up computed tomography (CT) and magnetic resonance image (MRI) in 2 months, the mass slightly increased in size, and a small part of low density or signal intensity appeared, despite the regular anti-TB treatment regimen. Surgical resection was performed, and the resected specimens revealed scattered and irregular-shaped seminoma cells with an intervening chronic granulomatous reaction. The aim of this article is to report a case of PMS in a young male patient who had a granulomatous reaction that mimicked a neoplastic population of cells leading to an erroneous diagnosis of the small biopsy. Therefore, awareness of the secondary changes that can mimic a primary lesion can help with an early correction of this misdiagnosis.

Primary mediastinal seminoma

“…Due to the slow growth of seminomas, most of them have been found large and bulky at the time of a diagnosis. Symptoms are not characteristic and there are patients in whom this type of tumor is diagnosed incidentally (2,3,(5)(6)(7)(8).…”

Thoracic SMARCA4‐deficient undifferentiated tumor with associated granulomatous reaction and response to pembrolizumab

“…18,21 Some seminomas occur in the mediastinum, and they consistently express SALL4. [23][24][25] Although the age group for SMARCA4-UT is older compared to seminoma, patients as young as F I G U R E 3 Immunohistochemical stains performed on the core biopsy. An H&E section (A) is included for reference (magnification Â200).…”

The Possibilities of Bronchoscopy and Endosonography in the Differential Diagnosis of Mediastinal Tuberculous and Metastatic Lesions

“…Так, по данным M. Feng et al [6], туберкулезный генез изменений, выявленный при ПЭТ-КТ у пациентов с подозрением на рецидив рака легкого, составляет почти 37% от всего объема ошибочно установленных диагнозов рака легкого. Описаны случаи как туберкулеза, ошибочно расцененного как лимфома [7], так и первичной семиномы средостения, изначально расцененной как гранулематозный процесс [8]. Нередки случаи реактивации туберкулезного процесса у пациентов с подтвержденным немелкоклеточным раком легкого на фоне приема таргетных препаратов, расцененные изначально как прогрессирование неопластического процесса [9].…”