Cutaneous and Subcutaneous Tumours of Small Pet Mammals—Retrospective Study of 256 Cases (2014–2021)

Abstract

Since small mammals are gaining popularity as pets in Poland, the number of tumour samples submitted for histopathological examination is quite high. This study was a retrospective analysis of cutaneous and subcutaneous tumours in small pet mammals submitted for histopathology in 2014–2021. The analysis included 256 tumours sampled from 103 guinea pigs, 53 rats, 43 pet rabbits, 21 ferrets, 17 hamsters, 8 degus, 5 African pygmy hedgehogs, 3 Mongolian gerbils and 3 chinchillas. Tumours were diagnosed based on routine histopathology, with additional immunohistochemistry when necessary. The results of this study revealed that the vast majority of cutaneous tumours in guinea pigs were benign, with a predominance of lipoma. Adnexal tumours constituted a significant percentage of cutaneous tumours in guinea pigs (24.3%, with the most common being trichofolliculoma), pet rabbits (46.5%, with the most common being trichoblastoma), ferrets (33.3%, mostly derived from sebaceous glands), hamsters (52.9%, with the most common being trichoepithelioma) and gerbils (66.7%, scent gland epithelioma). Soft tissue sarcomas were a predominant group of tumours in rats (52.8%, with the most common being fibrosarcoma), African pygmy hedgehogs (100%), degus (87.5%) and chinchillas (66.7%). Melanocytic tumours were only sporadically seen in small mammal pets. Mast cell tumours were diagnosed only in ferrets, while epitheliotropic T-cell lymphoma was diagnosed only in a hamster and a degu. In summary, malignant tumours constitute a significant percentage of cutaneous tumours in many species of small mammal pets. Therefore, each cutaneous tumour should be sampled for further cytologic or histopathologic diagnosis.

Use of chemotherapy in Syrian hamsters (Mesocricetus auratus) with epitheliotropic T‐cell lymphoma: Two cases (2021–2022)

“…1 In pet Syrian hamsters with tumours, the integument is the most commonly affected system, accounting for 52% of all tumours submitted for histopathological evaluation in four facilities. 2 However, only sporadic cases of cutaneous lymphoma have been reported in Syrian hamsters, [3][4][5][6][7] with a total of seven cases documented to be epitheliotropic T-cell lymphoma (ETCL). 4,6 Spontaneous visceral lymphoma is rarely reported, with the majority associated with hamster polyomavirus (HaPV) infection, which causes visceral lymphoma in younger hamsters.…”

“…2 However, only sporadic cases of cutaneous lymphoma have been reported in Syrian hamsters, [3][4][5][6][7] with a total of seven cases documented to be epitheliotropic T-cell lymphoma (ETCL). 4,6 Spontaneous visceral lymphoma is rarely reported, with the majority associated with hamster polyomavirus (HaPV) infection, which causes visceral lymphoma in younger hamsters. 3,[8][9][10] Cutaneous lymphoma can be classified into epitheliotropic and non-epitheliotropic lymphomas.…”

“…11,12 Epitheliotropic lymphoma is characterised as being T-cell in origin. 13 ETCL is reported in human beings 14,15 and multiple companion mammals, including dogs, 12,16,17 cats, [17][18][19] ferrets, 20 rabbits, 21,22 guinea pigs, 23,24 a degu, 4 a chipmunk, 25 a squirrel, 26 a hedgehog 27 and Syrian hamsters. 4,6 The aetiology of ETCL remains unknown.…”

“…13 ETCL is reported in human beings 14,15 and multiple companion mammals, including dogs, 12,16,17 cats, [17][18][19] ferrets, 20 rabbits, 21,22 guinea pigs, 23,24 a degu, 4 a chipmunk, 25 a squirrel, 26 a hedgehog 27 and Syrian hamsters. 4,6 The aetiology of ETCL remains unknown. 17,28 Clinical signs reported in Syrian hamsters include focal alopecia and scaling.…”

“…6,29 Diagnosis of the disease is based on histopathological evaluation showing epitheliotropism of the neoplastic lymphocytes. 4,29,30 Reported treatments in human beings, 15 dogs, 31 cats 17 and ferrets 32 include surgical removal of localised lesions and systemic or topical chemotherapies. However, treatment of ETCL in hamsters has not been documented in PubMed, Google Scholar or VIN databases.…”