Endolymphatic Sac Carcinoma In Situ in a Tokay Gecko (Gekko gecko)
An 11-year-old female tokay gecko (Gekko gecko) was presented for bilateral asymmetric swellings of the cervical region. Baseline hematologic and plasma biochemical analyses demonstrated anemia, hypercalcemia, hyperphosphatemia, and hypoalbuminemia. Whole-body radiographs revealed a mass effect and irregular mineralization in the region of the left endolymphatic sac. Fine needle aspiration of this region revealed many elongated calcium-based crystals with pointed ends, histiocytic inflammation, and clusters of epithelial cells, consistent with hyperplasia or neoplasia of the epithelium of the endolymphatic sac. The crystals were shown to be calcium carbonate by infrared crystallography. Given the advanced state of disease and inability to completely excise the mass due to the intimate association between the meninges and endolymphatic sac, the gecko was euthanized. Gross necropsy and histopathologic evaluation revealed carcinoma in situ of the left endolymphatic sac. To our knowledge, this is the first report of neoplasia of the endolymphatic sac in a reptile.Abstract
Dorsoventral radiographic image (A) and postmortem photograph (B) of the left endolymphatic sac (white arrows). (A) An eccentric, partially mineralized, soft tissue opacity mass effect is present in the left cervical region (white arrow). A diffuse mineral opacity is also present in the right endolymphatic sac (black arrow) and left and right inner ears (*). (B) A firm, pedunculated, tan mass expanded the lumen of the sac (white arrow). For reference, the heart (H) is positioned at the bottom left corner of this photograph. Bar = 1 cm.
Representative photomicrographs of cytologic smears of the aspirate from the mass in the left endolymphatic sac. (A) The direct smears consisted of numerous elongate oval-to-rectangular crystals with pointed ends, a few erythrocytes, and several clusters of round to polygonal epithelial cells (arrows). The crystals were identified as calcium carbonate on further testing. Wright's stain; bar = 50 μm. (B) The epithelial cells demonstrated mild-to-moderate anisokaryosis and anisocytosis and low numbers were binucleated. A macrophage containing many phagocytized crystals is also visible in this image (arrow). Wright's stain; bar = 10 μm.
Representative photomicrographs of the endolymphatic carcinoma in situ. (A) Sections consisted of papillary projections of neoplastic epithelial cells that were mostly arranged as a single layer of columnar epithelial cells overlying a fine fibrovascular stroma. Multifocally within the neoplasms there was disorganization with haphazard nuclear piling (white arrows) and formations of dense islands and lobules of columnarto-polygonal neoplastic cells (black arrows). Small numbers of mononuclear cells and granulocytes multifocally infiltrated the neoplastic stroma (black arrowhead). Hematoxylin and eosin (H&E); bar = 200 μm. (B) Neoplastic cells exhibited moderate anisocytosis and anisokaryosis with zero to four mitotic figures (white arrow) per high-magnification field. H&E; bar = 30 μm.
