The Use of Self-Inflating Hygroscopic Tissue Expanders to Facilitate Osteosarcoma Removal in a Massasauga Rattlesnake (Sistrurus catenatus)

Abstract

A 0.34 kg adult female Massasauga rattlesnake (Sistrurus catenatus) was presented for evaluation of a subcutaneous mass affecting the ventral scales. The mass was diagnosed as a sarcoma via punch biopsy with no evidence of metastasis on diagnostic imaging. Surgical margins of 1-2 cm were planned to achieve complete excision of the neoplasm. A technique for tissue expansion was employed due to concerns regarding the ability to close the surgical site without excess tension or dehiscence. Two 27 mm diameter × 5 mm hygroscopic self-inflating tissue expanders were placed subcutaneously under the lateral scales adjacent to the mass. Maximum skin expansion occurred over a four-week period, and no direct negative effects were noted. Excision of the primary mass was performed routinely five weeks after implant placement. Primary closure of the defect was achieved with minimal tension by incorporating the expanded skin. While the surgery was successful with no evidence of metastasis, the snake died of sepsis two weeks postoperatively. This is the first report of the use of self-inflating hygroscopic tissue expanders to help close a surgical defect in a reptile.

Figure 1

Self-inflating hygroscopic tissue expander (Oxtex Ltd.) before and after expansion.

Figure 2

Immediate postoperative (a) photograph and (b) dorsoventral radiograph of a Massasauga rattlesnake (Sistrurus catenatus) with two self-inflating hygroscopic tissue expanders implanted subcutaneously under the lateral scales.

Figure 3

(a) Photograph and (b) dorsoventral radiograph of a Massasauga rattlesnake (Sistrurus catenatus) showing maximal expansion of two self-inflating hygroscopic tissue expanders four weeks after implant placement.

Figure 4

Massasauga rattlesnake (Sistrurus catenatus). Intraoperative photograph taken after extraction of two self-inflating hygroscopic tissue expanders. The excess expanded skin is visible on the near side of the incision. There is a thin band of soft tissue between the two implant sites (arrow). The ventral surface of the neoplasm is displacing the ventral scales (arrowhead).

Figure 5

Postoperative photograph showing incorporation of expanded lateral skin into an osteosarcoma excision site in a Massasauga rattlesnake (Sistrurus catenatus).

Figure 6

Massasauga rattlesnake (Sistrurus catenatus). Low-magnification (20x) photomicrograph of a dermal osteosarcoma composed of a well-demarcated, expansile mass of haphazardly arranged spindle cells interspersed between irregular islands of bone and myxomatous matrix.