Pure mucinous (colloid) adenocarcinoma of the conjunctiva.

Primary mucinous carcinomas of the periorbital region are very rare and often require differential diagnosis of metastatic disease. We describe a case of pure mucinous adenocarcinoma arising in the subconjunctival stroma of the ocular fornix in a female patient with a longstanding history of bilateral ocular cicatricial pemphigoid. Histologically, the tumor was composed of predominantly goblet-like cells floating in pools of mucin separated by delicate collagenous septa. The initial suspicion was of primary cutaneous mucinous carcinoma and less likely endocrine mucin-producing sweat gland carcinoma, however the CK7-/synaptophysin-/chromogranin-immunoprofile did not confirm either of the two. Focal areas of the tumor demonstrated peripheral staining for p63 and CK5/6 suggestive of an in situ component. Additional studies showed that the tumor cells were positive for CK20, CDX2, villin and MUC2. Given the final immunophenotype of the tumor, metastatic lesion from the lower gastrointestinal tract had to be ruled out. Thorough clinicoradiological work-up did not reveal any other primary tumors or evidence of metastatic disease elsewhere. Unique histomorphology, the presence of an in-situ component and negative clinical investigation suggest that this is a primary mucinous adenocarcinoma arising in the ocular fornix. This case may represent the first report of this entity in the literature.