• Two benign acquired melanocytic lesions of the iris stroma had distinctive clinical and pathologic features. One tumor was loculated and polypoid, suggesting ectopic glandular tissue, while the other was a flat tumor with a rich surface capillarity. Both lesions histologically were composed of mononucleated, binucleated, and multinucleated hypopigmented epithelioid and elongated "myoid" cells, widely separated in a finely fibrillar eosinophilic stroma. The ultrastructural features of one case included hyperconvoluted nuclei, conspicuous cytoplasmic filaments and rare, filamentarystriated (leptomeric) structures, scant organelles and inclusions except for numerous mitochondria and glycogen granules, small and infrequent melanosomes, and a fibrillary extracellular matrix focally organized into banded basement membrane material.