Metastases to the testis are extremely rare. To our knowledge and after extensive literature review, only some 200 cases have been reported worldwide. Amongst these, the commonest ones are metastatic carcinoma of the prostate (34.6%), lung (17.3%), malignant melanoma (8.2%), colon (7.7%), and kidney (5.8%) [4]. In single cases, the organs of origin of the carcinoma were stomach, pancreas, penis, bladder, rectum, thyroid, ureter, bile duct, and liver. Occasionally, sarcomas and neuroblastomas have reportedly spread into the testis [5–8]. To our knowledge, although 7.7% of secondaries are from the colon, the appendix as original tumour-bearing organ has not yet been reported.
Adenocarcinoma of the appendix has generally a poor prognosis (5-year survival 50%) due to an early spread of disease that, in turn, is partially due to the low threshold of suspicion and difficulties of diagnosis prior to surgery [3]. It will mostly present and be diagnosed as an acute or chronic appendicitis, as it did in our case some two years ago. In spite of a relatively quick radical therapy in the form of hemicolectomy and adjuvant chemotherapy the patient relapsed with a distant metastasis into a rather unusual organ. The pathway of spread may have been haematogenously or lymphogenously. More likely though, in our case there may have been a continuous growth from the abdomen near the internal inguinal ring through the spermatic cord into the testis [9], as suggested by the histological involvement of the spermatic cord.
Clinically relevant is that the tumour did present and was treated for some time as an epididymo-orchitis. Indeed, the clinical picture, and the presence of inflammation and pain do not help to distinguish a benign from a malignant lesion [1]. Nor will the ultrasound be able to erase all doubt. We all learn that a persistent epididymitis can represent a tumour. In practice, this may need a reminder from time to time. In unclear testicular masses, even under the clinical picture of an epididymo-orchitis, a surgical exploration and/ or resection is indicated after initial but short antibiotic treatment has proven unsuccessful.