Cutaneous Iridophoroma in an Argentine Horned Frog (Ceratophrys ornata)
A 14-yr-old Argentine horned frog (Ceratophrys ornata) presented for evaluation of a chronic, cutaneous mass. A white, semifirm raised mass was present in the skin on the right cranial dorsum. Excisional biopsy was performed. Fine-needle aspiration cytology and histopathology were consistent with an iridophoroma, a type of chromatophoroma. Recurrence occurred and removal was repeated 4 months and again 2 yr following the initial surgery. The original mass did not have definitive criteria of malignancy but did extend to surgical margins, which may account for repeated local recurrence. Although chromatophoromas are relatively common cutaneous neoplasms in reptiles and amphibians, iridophoromas are rarely reported in amphibians. This is the first report of an iridophoroma in an Argentine horned frog.Abstract
Gross clinical appearance of an iridophoroma in an Argentine horned frog (Ceratophrys ornata). A raised, mottled white to brown, partially ulcerated cutaneous mass protrudes from the right cranial dorsal skin.
Histologic appearance of a surgically excised cutaneous iridophoroma in an Argentine horned frog (Ceratophrys ornata). A. Refractile pigmented round to slightly spindloid cells form solid sheets in the dermis. B. Pigmented crystalline material in the same field of view is birefringent under polarized light. Hematoxylin and eosin stain; 40× objective (bar = 25 µm).
Cytologic appearance of a fine-needle aspirate from a cutaneous iridophoroma in an Argentine horned frog (Ceratophrys ornata). A. Clusters (black arrows) and individualized cells have abundant cytoplasm filled with refractile, yellow–brown crystalline material. Inset: The same field of view shows birefringent crystalline material under polarized light. Diff-quik stain, 4× objective (bar = 200 µm). B. High magnification of an individualized cell with refractile, yellow–brown, crystalline material in the cytoplasm. A well-differentiated mast cell is included in the field at the left of the image. Inset: The same field of view under polarized light to demonstrate birefringent crystalline material. Diff-quik stain, 50× oil objective (bar = 20 µm).
