Melanophoroma in a Lichtenstein's green racer snake

Melanophoroma is a neoplasm of reptilian pigment cells, considered uncommon and part of a group of neoplasms called chromatophoromas. The objective of this work was to describe a case of melanophoroma in a free-living Lichtenstein's green racer snake (Philodryas olfersii), presenting with an ulcerative nodular neoformation in the integument of the head region. In the neurologic evaluation, a proprioceptive deficit was observed. Ultrasound, X-ray, and mass cytology examinations were performed. Radiographic and ultrasound findings of the tumor indicated infiltrative behavior, and cytology indicated a presumptive diagnosis of a melanocytic neoplasm. Based on the results of the examinations and the patient's clinical condition, euthanasia was chosen. At necropsy, there was a nodule measuring 4.5 × 2.5 × 2.0 cm, with a blackish-colored cut surface, mottled by gray areas, which infiltrated soft tissue and bone, and extended dorsally from the mouth to the cervical musculature. On microscopy, a non-delimited, non-encapsulated, and invasive neoplastic proliferation was observed, with moderate cellularity, which was predominantly composed of fusiform cells with distinct borders and foci of epithelioid cells. The cells had ample cytoplasm, which had a brown to black (melanocytic) granular pigment compatible with a melanophoroma. To the best of the authors' knowledge, this is a unique description of a melanophoroma in P. olfersii.