Intestinal Metastases from Unknown Primary Masquerading as Primary Colonic NeoplasmsDiagnostic Dilemma Elucidated by Detailed Clinical Evaluation

Abstract

Intestinal metastasis from unknown primary may simulate a primary colonic neoplasm in its clinical presentation. The gross histopathological examination may also mimic primary intestinal pathology. The diagnostic dilemma is furthered by paucity of available knowledge due to the limited literature. This article discusses three such cases, all of which clinically presented with bowel symptoms, either in the form of acute abdomen or intestinal obstruction. The imaging studies pointed towards an intestinal pathology. Although the initial presentation was dubious, on delving into the medical and surgical history, all of them had a previous known malignant neoplasm on different sites like skin, ovary and cervix. The diagnosis of intestinal metastasis of melanoma, High Grade Serous Carcinoma (HGSC) of ovary and Squamous Cell Carcinoma (SCC) of cervix, respectively, were supported by suggestive histomorphology and ancillary studies like immunohistochemistry in one of the cases. The most alluring of the above three cases was that of intestinal metastasis from melanoma, where lack of melanin pigment made the histological diagnosis difficult. After retrieving medical history along with diffuse S100 and HMB45 positivity, definitive conclusion could be opined. Thus, clinical history of the patient was the cornerstone for definitive diagnosis in all of the three cases. Primary colonic neoplasms and intestinal metastasis from previous known malignant neoplasms have totally different clinical and prognostic outcomes. So, identification of these cases is extremely important from treatment point of view. It is possible only based on detailed clinical evaluation, clear suspicion, suggestive histomorphology and suitable ancillary investigations.