An 11-year-old male Egyptian fruit bat (Rousettus aegyptiacus) was found on the floor of the bat exhibit, unable to fly. The animal was presented with superficial bite injuries to the dorsal and ventral thorax and unilateral swelling of the skin, muscles, and appendages on the right side of the body. Culture yielded heavy mixed growth of multiple bacterial isolates. Cytologic examination of wound exudate was non-diagnostic. The wounds failed to heal with empirical antibiotic therapy, thus biopsy samples were obtained. Biopsies confirmed cutaneous lymphosarcoma present within the dermis and skeletal muscle. The animal was humanely euthanatized and submitted for necropsy.
Necropsy revealed that the neoplasm extended on the right side of the body from the ear to the pubis bone, both ventrally and dorsally. Histopathology revealed a densely cellular, poorly demarcated, and unencapsulated mass expanding and infiltrating the dermis, subcutis, and skeletal muscle. Cells were arranged in sheets and exhibited moderate pleomorphism. In addition, the neoplasm infiltrated the salivary glands and cervical lymph nodes on the right side and expanded the lamina propria of large airways in the lung.
Immunohistochemical staining (IHC) was performed multiple times, with canine- and feline-specific antibodies in an attempt to further characterize the cell type of origin as either T (CD3+) or B (CD79+) lymphocytes. Unfortunately, IHC was unrewarding. Species differences likely explain the inability to further characterize the cell type of origin.
Neoplasia is uncommon in chiropterans.2 To the authors’ knowledge, this report documents the first case of cutaneous lymphosarcoma in the Rousettus species.1,3,4
1. Andreasen, C., and J.R. Dulmstra. 1996. Multicentric malignant lymphoma in a pallid bat. J Wildl Dis. 32:545–547.
2. Heard, D.J. 2003. Chiroptera. In: Fowler, M.E., and R.E. Miller (eds.). Zoo and Wild Animal Medicine, 5th ed. WB Saunders, St. Louis, Missouri. 315–333.
3. McKnight, C.A., A.G. Wise, R.K. Maes, A. Howe, A. Rector, M. Van Ranst, and M. Kiupel. 2006. Papillomavirus-associated basosquamous carcinoma in an Egyptian fruit bat (Rousettus aegyptiacus). J Zoo Wildl Med. 37:193–196.
4. Siegal-Willott, J., D.J. Heard, N. Sliess, D. Naydan, and J. Roberts. 2007. Microchip-associated leiomyosarcoma in an Egyptian fruit bat (Rousettus aegyptiacus). J Zoo Wildl Med. 38:352–355.