Neuroendocrine tumours metastatic to the uvea: diagnosis by fine needle aspiration biopsy.

BACKGROUND: Uveal metastasis from a neuroendocrine tumour is rare and can simulate other primary or metastatic uveal tumours, both clinically and cytomorphologically. We describe four cases of uveal metastasis from a neuroendocrine tumour diagnosed by fine needle aspiration biopsy (FNAB).
METHODS: Four patients were referred for evaluation of a recently detected fundus mass. Two patients had a history of malignant, non-ocular, neuroendocrine neoplasms (Merkel cell carcinoma and lung carcinoid in one patient each). The third patient had a mediastinal mass that had been biopsied inconclusively, while the last patient reported a persistent cough.
RESULTS: Ophthalmic examination revealed an amelanotic ciliochoroidal mass in 2 cases and a lightly melanotic and a pale orange choroidal mass in 1 case each. Partial, non-rhegmatogenous, retinal detachment was present in 3 patients. Ocular ultrasonography revealed moderate to high internal reflectivity of the mass in 3 cases and low internal reflectivity in the 4th. Our differential diagnosis in all cases was metastatic carcinoma versus primary uveal melanoma. FNAB of the intraocular mass was performed in all patients to establish a pathologic diagnosis and guide subsequent management. Cytomorphology and immunohistochemical profiles of the aspirates were consistent with metastatic neuroendocrine neoplasms in all patients. Our final diagnosis was metastatic lung carcinoid in 2 patients and metastatic Merkel cell carcinoma and small cell lung carcinoma in 1 patient each. Immediately after FNAB, the intraocular tumour was treated by plaque radiotherapy (3 patients) or fractionated external beam radiotherapy (1 patient). All tumours treated regressed satisfactorily. Two patients expired due to widespread lung carcinoid 11 and 12 months after our initial evaluation respectively. The other two patients are still alive after 38 and 64 months respectively.
CONCLUSIONS: Neuroendocrine tumours are a heterogeneous group of neoplasms whose diagnosis ultimately depends on the identification of specific cell markers (e.g., neuron-specific enolase, chromogranin, synaptophysin), hormones and neurotransmitters (e.g., gastrin, serotonin, adrenocorticotrophic hormone [ACTH]). FNAB with immunohistochemical stains for neuroendocrine markers can establish a pathologic diagnosis in cases of uveal metastasis from a neuroendocrine tumour. To our knowledge, our patient with Merkel cell carcinoma is the first pathologically proven case of uveal metastasis from this primary malignancy.