Pure Adenocarcinoma with Intestinal Differentiation of The Testis as The First Presentation of a Testicular Teratoma: A Case Report with Literature Review of Management

Pure adenocarcinoma is a somatic-type malignancy that comes from a germ cell tumor and is extremely rare but has been reported. It is usually seen as sarcoma, and less often as carcinoma. This rare phenomenon is generally attributed to the development of a teratomatous component. In most cases, the diagnosis remains straightforward due to the mixing of different germ cell tumor parts and the existence of germ cell neoplasia in situ (GCNIS). But, there are some rare instances where metastatic carcinoma to the testis could be something more. This case presentation discusses a 35-year-old man who had a testicular tumor of adenocarcinoma with enteric features, which looked like metastatic colorectal carcinoma. GCNIS was found in the background testicular tissue, and fluorescence in situ hybridization for chromosome 12p abnormalities showed the presence of i(12p) in the testicular adenocarcinoma, which supports a shared germ cell origin. After the retroperitoneal lymph node dissection, it was found that there were metastatic deposits made up of mucinous adenocarcinoma. Extensive clinical workup helped exclude metastasis from another primary, particularly the GI tract. Our report indicates that adenocarcinoma of intestinal type in an orchiectomy specimen, although usually strongly suggestive of metastasis from a gastrointestinal tract primary, maybe a primary testicular neoplasm of germ cell tumor origin. The patient was treated with radial orchidectomy with retroperitoneal metastasectomy followed by somatic-type malignant histology-directed chemotherapy for colorectal adenocarcinoma. The patient remained in complete remission for a 3.5-years follow-up period.