Characterization of an orbital melanoma and mucosa associated lymphoid tissue (MALT) lymphoma by dual phase N-isopropyl-p-I-123 iodoamphetamine.

Usefulness of N-isopropyl-p-I-123 iodoamphetamine (I-123 IMP) for the detection of malignant melanoma and malignant lymphoma is well known. The appropriate interval from administration until image acquisition is unusual because the accumulation mechanism is different. We present a case of choroidal melanoma of the right orbit with a history of low-grade mucosa-associated lymphoid tissue lymphoma of the left lacrimal gland. She was followed with magnetic resonance imaging and dual phase I-123 IMP imaging 3 times. Viability of the melanoma was estimated by I-123 IMP delayed image obtained 24 hours after intravenous injection. In spite of cryosurgery twice, the accumulation of the tracer remained unchanged. Subsequent tumor excision proved the lesion to be a viable malignant melanoma. On the other hand, posttherapeutic mucosa-associated lymphoid tissue lymphoma of the left lacrimal gland was followed by the early image obtained 20 minutes after radionuclide injection. The accumulation increased gradually and the recurrence was pointed out. In the same way, magnetic resonance imaging examination was undertaken 3 times. Both lesions were obvious, but the findings were entirely unchanged in each examination.