Summary

A 45-year-old man presented with right-sided testicular swelling and pain. An examination found a tender, firm right testis, a clinically normal left testis and no palpable lymphadenopathy. Tumour and inflammatory markers were within normal limits. A scrotal ultrasound scan showed an intratesticular, avascular lesion measuring 4.4×2.6×1.8 cm. A CT scan of his chest/abdomen/pelvis (CT C/A/P) showed no metastatic or primary lesions. An elective right-inguinal orchidectomy was subsequently performed. Histopathology showed a cystic mucinous tumour lined with intestinal-type epithelium. Differentials of metastatic adenocarcinoma, possibly of a gastrointestinal origin, a monodermal teratoma, or a borderline mucinous tumour of the testicle (BMTT) were considered. Following 12 p genetic studies and a colonoscopy, both of which found no abnormalities, a presumptive diagnosis of a BMTT was made. The patient is to have an annual urological review with a CT C/A/P and 5 yearly colonoscopies.