Signet ring cell-type adenocarcinoma arising in a mature teratoma of the testis

Abstract

A 48-year-old male who presented with an enlarged right scrotum was diagnosed with malignant transformation of testicular teratoma. Physical examination revealed a right scrotal mass of hard consistency with no inguinal lymphadenopathy. Since prepuberty, his right testis had been larger than the left one, with no pain or tenderness. Computed tomography and bone scan revealed retroperitoneal lymphadenopathy and multiple bone metastases. Right orchiectomy was performed immediately, and a pathological examination revealed a mature teratoma associated with adenocarcinoma, showing signet ring cell differentiation. Cisplatin-based combination chemotherapy was administered; however, the metastatic lesions progressed, and the patient succumbed to the disease after 15 months. Only a few cases of primary malignant transformation of teratoma in the testis have been reported, and this is the first case report of primary malignant transformation of teratoma in the testis with signet ring cell-type differentiation.

Figure 1

Enhanced pelvic CT shows a 5.0 × 5.0 cm mass in the right testis (white arrows). The tumor is round with a thick wall and is irregularly enhanced in contrast to the low-density internal area, suggesting fat and focal calcifications. The tumor is accompanied by a mild hydrocele (A). An enlarged retroperitoneal lymph node (1.7 cm) is shown in the aortocaval area (black arrows) (B).

Figure 2

Bone scan shows areas of multiple metastases, including the 2nd and 4th lumbar vertebrae, sternum, right scapula and ribs.

Figure 3

Mature teratoma associated with adenocarcinoma showing intestinal differentiation. (A) Gross appearance of the tumor. Nearly the whole testis is replaced by tumor mass and fibrous tissue. The cut surface of the mass shows yellowish, white grumous material, occasional mucoid material and some hair. (B) Microscopic findings of the tumor. The squamous epithelium is converted to columnar cells (arrow). Abundant glandular structures are noted beneath the epithelium. Tumor cells show irregularity of glandular structure, and some cells reveal a scattered pattern. The nucleolus is dense and displaced by cytoplasm, an indication of signet ring type adenocarcinoma (H&E staining).

Figure 4

Whole body PET/CT shows hypermetabolic lesions with fluorodeoxyglucose uptake at the sternum, lumbar vertebrae, rib and aortocaval lymph node, with no abnormal uptake in the stomach and intestine.

Figure 5

Thoraco-lumbar CT shows an osteolytic lesion extending into the paravertebral area on the left side of the 4th lumbar vertebrae.