Seminoma presenting as a solitary metastasis in gastric mucosa with regressed testicular mass

Abstract

Gastric involvement by seminoma is extremely rare and all the reported cases were associated with bulky retroperitoneal disease or occurred late as part of advanced disease. We report a unique case of seminoma presenting as gastric mucosal metastasis. The diagnosis of this case was complicated by no residual testicular tumor or pelvic/retroperitoneal lymph nodes metastasis and no available specific serum markers. The histological morphology and immunostains allowed the correct diagnosis to be made in this case. This case highlights the rare manifestation of seminoma, which appears to be a primary tumor of an unusual site of germ cell tumor metastasis.

Fig. 1

A, the coronal (upper) and axial (lower) abdominal CT with iv-contrast demonstrated nodular thickening of the gastric fundus and gastroesophageal junction B, microscopic examination at low magnification showing fragments of gastric mucosa focally being infiltrated by a neoplastic process. C, microscopic examination at high magnification showing the malignant cells with large nuclei, prominent nucleoli and a small amount of basophilic-to-clear cytoplasm. D, the immunostain showing the tumor cells positive for CD117. E, the immunostain showing the tumor cells positive for OCT3/4.

Fig. 2

A, positron emission tomography (PET) scan showing a FDG avid (SUVmax 7.4) focus at gastric fundus, corresponding to the nodular thickening on the CT, and a FDG avid (SUVmax 8.7) focus in the left testicle (arrows). B, scrotal ultrasound showing a 1.3cm ill-defined lobulated hypoechoic solid mass, corresponding to the aforementioned FDG-avid lesion. There is also microlithiasis in the left testis. C, microscopic examination of the left testis demonstrating granulomatous inflammation, fibrosis and hyalinized scar.