Choroidal metastasis as the initial manifestation of a pigmented neuroendocrine tumor

We report the case of a 77-year-old woman in whom choroidal metastasis was the initial manifestation of a primary neoplasm presumed to be a pigmented pulmonary carcinoid tumor. The tumor initially was misdiagnosed cytological ly and pathologically as a choroidal melanoma because it contained intrinsi c melanin pigment. Positive immunoreactivity for cytokeratin, synaptophysin , chromogranin, and calcitonin and the presence of dense-core neurosecretor y vesicles disclosed by electron microscopy established that the metastasis was a neuroendocrine tumor. Findings from systemic evaluation suggested th at the primary tumor was located in the lung. The patient subsequently deve loped an intradural paraspinal metastasis, which also contained melanin pig ment. The latter observation confirmed that the melanin in the uveal metast asis was intrinsic and did not represent secondary phagocytosis by tumor ce lls. Metastases from pigmented tumors of nonmelanocytic derivation are exce edingly rare but present a major diagnostic challenge to ocular pathologist s and cytopathologists if the diagnosis is not suspected. Confirmatory immu nohistochemical analysis should be obtained when a pigmented choroidal tumo r thought to be a melanoma has atypical features.