Clinical, histopathological, and immunohistochemical studies of histiocytic sarcoma in four-toed hedgehogs (Atelerix albiventris): A retrospective study

Disseminated histiocytic sarcoma in a degu (Octodon degus)

A 7-year-and-8-month-old, male degu (Octodon degus) with anorexia, depression, and labored breathing was found to have a thoracic effusion and enlargement of the right testis on radiographic examination. Despite treatment, the animal died. At necropsy, hepatomegaly, splenomegaly, and multifocal nodules on the intestinal serosa and mesentery were observed. Histologically, the foci were densely cellular invasive neoplasms composed of sheets of round to polygonal cells, with occasional multinucleated giant cells. Immunohistochemically, the neoplastic cells were immunopositive for ionized calcium-binding adapter molecule 1, human leukocyte antigen-DR, and CD204. These findings were consistent with disseminated histiocytic sarcoma.

Dermatologic Diseases of Four-Toed Hedgehogs

Dermatologic diseases are frequently diagnosed in the four-toed hedgehog. Common clinical signs include spine loss, scales and crusts, pruritus, alopecia, and masses. Caparinia tripilis, family Psoroptidae, is the most common mite affecting hedgehogs, and is diagnosed via light microscopy. Dermatophytosis from Trichophyton erinacei infection is a common zoonotic dermatologic disease in pet hedgehogs. Diagnosis is through fungal culture. Neoplasia is another major cause of dermatologic diseases in four-toed hedgehogs. The diagnostic approach typically begins with a fine-needle aspirate but often requires a biopsy for a definitive diagnosis.

Multiple Distinct Neoplasms in a North African Hedgehog (Atelerix algirus)

This paper describes the clinical and pathological features of 4 different tumors, located in the integumentary, digestive, and endocrine systems, presenting in a North African hedgehog (Atelerix algirus). A 3.5-year-old female hedgehog was presented with a cutaneous mass on the right flank. The lesion consisted of a well-differentiated dermal mast cell tumor with no recurrence and metastasis after complete surgical excision. Six months later, the hedgehog developed a mass in the left lower jaw, lethargy, anorexia, and progressive weight loss. Clinical and radiographic evaluations revealed swelling, ulceration, displacement, and destruction of subjacent bone tissue, and the animal died 1 month after the onset of clinical signs. At necropsy, 2 neoplasms in the oral cavity (squamous cell carcinoma and histiocytic sarcoma) and multiple myelolipomas in the adrenal glands were detected. Metastasis of the oral squamous cell carcinoma was observed in the lungs. Although neoplasms are frequent in this species, and more than 1 type of tumor in a single individual has been occasionally reported, this is the first description of both myelolipoma and multiple concurrent neoplasms involving various organs and different cellular origins in a hedgehog.

Clinical course and pathologic study of retrobulbar histiocytic sarcoma in a central bearded dragon (Pogona vitticeps)

A central bearded dragon (Pogona vitticeps) presented with periorbital swelling and exophthalmos. A retrobulbar mass was detected, and enucleation with the mass was performed. Histologically, the mass was composed of a dense sheet and interlacing bundles of round to polygonal to short spindle-shaped cells with occasional bizarre mononuclear and multinucleated giant cells. Immunohistochemically, the neoplastic cells had various degrees of membranous and/or cytoplasmic granular reactivity to anti-ionized calcium-binding adapter molecule 1 and anti-CD204 antibodies. Ultrastructurally, the neoplastic cells had irregular nuclei and abundant cytoplasm with membrane-bound electron-dense lysosomes and endoplasmic reticula. These findings were consistent with a histiocytic sarcoma. The present study provided a detailed description of retrobulbar histiocytic sarcoma for the first time in a central bearded dragon.

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

Simple Summary

Several species of small mammals are very popular as companion pet animals and therefore demand professional veterinary care, including proper diagnostic and treatment procedures. The incidence of neoplastic diseases in companion pet animals has increased over time, as it has in humans. The aim of this study was to evaluate the incidence of cutaneous tumours in small mammal pets, including guinea pigs, rats, pet rabbits, ferrets, hamsters, degus, African pygmy hedgehogs, Mongolian gerbils and chinchillas, submitted for histopathology in 2014–2021. Malignant tumours represented the predominant group of cutaneous tumours in rats, African pygmy hedgehogs, degus and chinchillas, and represented a significant percentage of lesions in guinea pigs, pet rabbits, ferrets, hamsters and Mongolian gerbils. We also described the first case of melanocytoma in a pet rabbit, epitheliotropic T-cell lymphoma in a degu, cutaneous histiocytic sarcoma in a Mongolian gerbil, fibrosarcoma in two chinchillas and epithelioid haemangioma in a chinchilla. The incidence of malignant neoplasms among spontaneous integumentary tumours submitted for histopathology is high in many species of small mammal pets. Therefore, each cutaneous tumour should be sampled for further diagnosis and treatment.

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.