Spontaneous tumours in captive African hedgehogs (Atelerix albiventris): a retrospective study

Case report: Abdominal mesothelioma in Atelerix albiventris

Hedgehogs, as exotic species, are more susceptible to various neoplastic conditions affecting diverse bodily systems, particularly the tegumentary, hemolymphatic, and digestive systems. Among these conditions, epithelial tumors are the most prevalent, followed by round cell tumors and mesenchymal tumors. A striking characteristic is the malignant nature of over 8% of these tumors, leading to a generally unfavorable prognosis. This study aims to present a unique case involving a 2.5 year-old male African pygmy hedgehog in Concepción, Biobío District, Chile, diagnosed with a mesenchymal neoplasia originating from mesothelial cells. The hedgehog presented to the veterinary clinic with acute abdominal pain, prompting ultrasound imaging, and comprehensive cytological, histopathological, and immunohistochemical analyses. During abdominal ultrasound, a mass was observed, and its cytological examination revealed the presence of malignant cells. The histopathological examination unveiled a diffuse mesothelial cell tissue interwoven with abundant fibrous tissue and small cysts containing serous fluid, all enveloped by flattened or cuboidal cells of mesothelial origin. Immunohistochemistry further confirmed the diagnosis, demonstrating positive immunostaining for calretinin and mesothelin markers, corroborating the diagnosis of fibrous malignant peritoneal mesothelioma. This case highlights the complexity of neoplastic conditions in hedgehogs and emphasizes the importance of multimodal diagnostic approaches for accurate identification and understanding of these rare diseases.

A case of nerve sheath tumor followed by multicentric high-grade T-cell lymphoma in an African pygmy hedgehog (Atelerix albiventris)

A 3-year-old intact male African pygmy hedgehog was presented at the Teaching Hospital of the Faculty of Veterinary Medicine, University of Belgrade, with a growth on the left side of its abdomen. After clinical examination, the mass was surgically removed, and histopathological findings indicated a nerve sheath tumor. The hedgehog fully recovered after surgery and was euthanized eight months later due to the appearance of multicentric changes in the internal organs. Further necropsy and macroscopic, cytologic, histopathologic, and immunohistochemical findings revealed that the tumor was a multicentric high-grade T-cell lymphoma. This is an unusual case of an African pygmy hedgehog with two different neoplasms-a nerve sheath tumor followed by lymphoma.

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.

Identification and characterization of the genome of a papillomavirus from skin lesions of four-toed hedgehogs (Atelerix albiventris)

The present study describes the clinical and pathological characteristics of skin lesions in two four-toed hedgehogs (Atelerix albiventris). We performed inverse PCR to identify the genome of papillomavirus (PV) in the skin lesions and subsequently sequenced the full genome of the virus, which was tentatively named Atelerix albiventris papillomavirus 1 (AalbPV1). The overall sequences of the viral genomes of both four-toed hedgehogs were identical. This study first identified the presence of a novel PV in Japanese four-toed hedgehogs and provided genetic information about this virus.

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.

Histopathological Features of Myxoid Pleomorphic Liposarcoma in an African Pygmy Hedgehog (Atelerix Albiventris)

Myxoid pleomorphic liposarcoma is characterized by pathological features of both pleomorphic liposarcoma and myxoid liposarcoma, as the name suggests. In this case, a myxoid pleomorphic liposarcoma was observed in a 5-year-old male African pygmy hedgehog. It consisted of ~60% of the myxoid substance area with proliferating round cells and ~30% of pleomorphic neoplastic cells. The subject presented with extrapulmonary metastasis, but a good prognosis during 6 months of follow-up, which is similar to the characteristics of myxoid liposarcoma. The histopathological features of myxoid pleomorphic liposarcoma may reflect the features of either myxoid liposarcoma or pleomorphic liposarcoma depending on the proportion of each histopathological feature. The proportion of the pleomorphic area and the myxoid area may offer information on the prognosis and metastasis of myxoid pleomorphic liposarcoma, which will be helpful for setting up a treatment plan. Thus, analyzing the proportion of pleomorphic area and myxoid area could be suggested as one of the ways to predict clinical outcomes. In addition to the fact that this is the first case of a myxoid pleomorphic liposarcoma in hedgehogs, this case is meaningful, considering the unique histopathological characteristics and rare incidence of myxoid pleomorphic liposarcoma that could be important in humans as well.

Pathological Findings in African Pygmy Hedgehogs Admitted into a Portuguese Rehabilitation Center

Most of the pathologies that affect hedgehogs are diagnosed postmortem; thus, it is essential to share knowledge between clinicians and pathologists in order to recognize predispositions to diseases and to establish adequate diagnostic and therapeutic plans. This study aimed to describe the most relevant postmortem pathological conditions in a group of six rescued African pygmy hedgehogs, performed over a period of four months. Hedgehogs were submitted to necropsy examinations and subsequent histopathological analyses. Microscopically, all the studied hedgehogs revealed alterations in one or more organ systems. Although a significant and diverse number of pathological conditions were obtained, this study focused on less common or more relevant pathologies found in African pygmy hedgehogs-namely, wobbly hedgehog syndrome, squamous cell carcinoma and mast cell tumors. Furthermore, this study constitutes the first report of Mycobacterium spp. in hedgehogs in Portugal, the second report of follicular thyroid carcinoma in an African pygmy hedgehog, the description of a lipoid pneumonia for the first time in this species and a lung adenocarcinoma-a pathology rarely reported in African pygmy hedgehogs.

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.

Surgical and medical management of an oral spindle cell sarcoma in an African hedgehog (Atelerix albiventris)

A 2.5-year-old male African hedgehog (Atelerix albiventris) presented with an intraoral, soft tissue mass overlying the left mandible. A computed tomography scan and subsequent fine needle aspirate suggested a malignant spindle cell tumour. The tumour was excised with a partial hemimandibulectomy. Histopathology demonstrated an incompletely excised spindle cell sarcoma. The hedgehog underwent adjuvant therapy consisting of intravenous carboplatin and oral lomustine, followed by palliative radiation therapy once tumour recurrence was noted on follow-up surveillance. Radiation therapy was initially successful in decreasing tumour size, but the hedgehog re-presented a month later acutely non-ambulatory paraparetic with a distal right antebrachial mass. Diagnostics including radiographs and fine needle aspirate were consistent with metastatic neoplasia and humane euthanasia was elected.

Cutaneous papilloma and multicentric squamous cell carcinoma in four-toed hedgehogs (Atelerix albiventris)

Skin lesions possibly caused by Papillomavirus infections in two four-toed hedgehogs are described. In case 1, there was a papillary mass on the right hind limb. Histologically, the mass was consistent with a viral papilloma. In the other case, multifocal papillary masses with erosions and ulcers were found throughout the body, mainly on the extremities. Histology showed continuative lesions composed of acanthosis, Bowenoid in situ carcinoma, and squamous cell carcinoma, with abrupt transitions between the lesions. In both cases, keratinocytes in the granular layer infrequently had features of koilocytes and intranuclear inclusion bodies, and immunohistochemical staining was positive for anti-human papillomavirus antibody. To the best of the authors’ knowledge, this is the first pathological documentation of possibly papillomavirus-associated skin lesions in four-toed hedgehogs.

Ovarian mixed germ-cell tumor comprising mature teratoma and embryonal carcinoma in a four-toed hedgehog (Atelerix albiventris)

This report describes the clinical and histopathological characteristics of a rare mixed germ-cell tumor comprising teratoma and embryonal carcinoma in the left ovary of a 10-month-old four-toed hedgehog, with chief complaints of loss of appetite and lethargy. Laparotomy revealed a swollen left ovary with small disseminated peritoneal nodules, and bilateral ovariohysterectomy was performed. The left ovary had a mature teratoma with well-differentiated fat, bone, cartilage, salivary gland, trachea, keratin cyst, and nervous tissues, and an embryonal carcinoma consisting of poorly-differentiated epithelial cells arranged in tubular, alveolar, or solid patterns. Immunohistochemically, the embryonal carcinoma cells were positive for placental alkaline phosphatase and c-KIT. This is the first case of mature teratoma with embryonal carcinoma in the ovary of a hedgehog.

Wobbly hedgehog syndrome with disseminated histiocytic sarcoma and lateral ventricular meningioma in an African pygmy hedgehog

An 8-mo-old male African pygmy hedgehog was anorectic and ataxic; physical examination revealed tetraparesis and a gangrenous left hindlimb. Analgesic and supportive care were administered, but the animal died 3 d after presentation. Postmortem examination revealed a histiocytic sarcoma in a mesenteric lymph node with metastasis to several organs, multifocal vacuolation in the cerebral and cerebellar white matter, and a meningioma in the left lateral ventricle. We diagnosed wobbly hedgehog syndrome (WHS) with disseminated histiocytic sarcoma and lateral ventricular meningioma. Ventricular meningioma, a rare neoplasm in veterinary and human patients, has not been reported previously in hedgehogs, to our knowledge. The neurologic signs in our case were probably caused by the WHS-related vacuolar lesions and are consistent with those of reported WHS cases. Duration of illness was shorter than is typical of WHS cases, which might be related to the disseminated histiocytic sarcoma. Clinical relevance of the lateral ventricular meningioma was not evident because the ventricular mass was localized and not invasive.

Disseminated Haemophagocytic Histiocytic Sarcoma in an African Pygmy Hedgehog (Atelerix albiventris)

A 3-year-old intact male African pygmy hedgehog (Atelerix albiventris) was found dead shortly after clinical onset of screaming, aerophagia and lethargy. On gross examination, the spleen was dark red and friable, and the liver was markedly enlarged with a prominent lobular pattern and multiple white nodules. Histopathological examination of liver and spleen revealed dense infiltrates of highly pleomorphic neoplastic, round to polyhedral cells with overt erythrophagocytosis. Similar neoplastic cells were found in the sinuses of the abdominal lymph nodes and in blood vessels in the heart, lung, brain and kidneys. Immunolabelling for CD204 confirmed the histiocytic origin of the neoplastic cells. To our knowledge, this is the first report of a disseminated haemophagocytic histiocytic sarcoma in a hedgehog.

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

Histiocytic sarcoma was investigated histopathologically and immunohistochemically in 17 four-toed hedgehogs (Atelerix albiventris), along with a review of their clinical data. Cases were histopathologically classified into two types: round-polygonal cell type (6 cases) and spindle cell type (11 cases). Round-polygonal cell type was found in visceral organs such as the spleen, lymph nodes, and more, and most cases of this type were consistent with disseminated histiocytic sarcoma. On the other hand, spindle cell type occurred mainly in skin, and almost all cases were consistent with localized histiocytic sarcoma. The prognosis of patients with round-polygonal cell type appeared worse than that of spindle cell type. Immunohistochemically, neoplastic cells of spindle cell type showed stronger reactivity against human leukocyte antigen-DR than round-polygonal cell type. Neoplastic cells of all cases showed strong reactivity against ionized calcium-binding adapter molecule-1 (Iba-1) and various reactivities against cluster of differentiation (CD) 204. Regardless of morphological classification, most tumor cells were negative for CD163, suggesting that this marker is less effective for the diagnosis of histiocytic sarcoma. The results of this study suggest that Iba-1 is the most effective marker for histiocytic sarcoma.

Eosinophilic Leukaemia and Systemic Mycobacterium marinum Infection in an African Pygmy Hedgehog (Atelerix albiventris)

A two-year-old male African pygmy hedgehog (Atelerix albiventris) presented with lethargy and anorexia. Ultrasonographic and radiographic examinations revealed splenomegaly and pneumonia, respectively. Prominent leucocytosis, consisting mainly of large atypical eosinophils, was observed in a peripheral blood smear. Necropsy revealed a black scab on the left hindlimb, which was swollen, an enlarged left inguinal lymph node, firm oedematous lungs, splenomegaly and multiple nodules in the lung, spleen and liver. Histopathologically, infiltration of numerous eosinophils was seen in lung, spleen, liver, kidney, lymph node and adrenal medulla tissues. Necrotizing granulomatous lesions, with intralesional acid-fast bacilli, were found in the lung, spleen, liver, left inguinal lymph node and left hindlimb. Mycobacterium marinum was identified by broad-range polymerase chain reaction targeting of the bacterial 16S rRNA gene. To the best of our knowledge, this is only the second reported case of systemic M. marinum infection in any mammalian species.

Primary localized histiocytic sarcoma of the lumbar vertebrae in a four-toed hedgehog (Atelerix albiventris)

We describe a case of primary localized histiocytic sarcoma of the lumbar vertebrae in a four-toed hedgehog. The case showed aggressive osteolysis of lumbar vertebrae on radiography, and a soft-tissue mass effacing this region was noted, suggesting a neoplastic lesion. No metastatic lesions were apparent. Antemortem diagnosis was challenging, and necropsy was performed. Histopathological and immunohistochemical findings were consistent with localized histiocytic sarcoma. This report provides documentation of the clinical and pathologic features of an unusual form of histiocytic sarcoma localizing to lumbar vertebrae in a four-toed hedgehog.

Histological and Immunohistochemical Features of Normal Histiocytes and Langerhans Cells, and Histiocytic Sarcomas in Four-Toed Hedgehogs (Atelerix albiventris)

Histiocytic sarcoma (HS) is a haematopoietic tumour of histiocyte origin that has been sporadically reported in four-toed hedgehogs (Atelerix albiventris). The present study aimed to investigate clinical, gross, histopathological and immunohistochemical features of HS in eight hedgehogs. Histological and immunohistochemical features of normal histiocytes and Langerhans cells (LCs) of hedgehogs were also investigated. HLA-DR-, Iba-1- and E-cadherin-positive LCs were observed in the epidermis, while Iba-1- and CD204-positive histiocytes were detected in the lymph nodes and spleen of normal hedgehogs. Localized HS (six cases) developed in the skin and spleen, while disseminated HS (two cases) occurred in the intestine. Tumour cells of disseminated HS were also distributed within the mesenteric lymph nodes, liver, kidney, spleen, lung and adrenal glands. Tumour cells of both localized and disseminated HS were composed of histiocytic cells, spindle to pleomorphic cells, multinucleated giant cells and erythrophagocytic cells. Most tumour cells were immunopositive for Iba-1, CD204 and lysozyme. A small number of tumour cells were positive for E-cadherin and CD208, and the tumour cells in one case were positive for HLA-DR. These results suggest that the tumour cells have variable features of histiocyte origin, including dendritic cells, LCs and macrophages. The behaviour of HS in the hedgehog was very aggressive, and 50% of cases died within 90 days of resection. The present study also highlighted the tendency for local tumour recurrence in localized cutaneous HS cases, suggesting a requirement for a long-term follow-up after excision.

Geriatric Hedgehogs

African hedgehogs are susceptible to aging changes like those of other small exotic mammals. Common conditions of the geriatric hedgehog include heart disease, chronic renal disease, and dental/periodontal disease. Hedgehogs are unique in that they have an unusually short life span and a propensity for neoplasia. These 2 factors make it especially common for exotic animal practitioners to encounter geriatric hedgehogs affected by one of the many conditions outlined in this article.

Selected Emerging Diseases of Pet Hedgehogs

Pet hedgehog medicine and surgery is a rapidly evolving field, with some novel conditions and re-emerging diseases being reported in the literature in recent years. Skin disease and neoplasia are commonly found in African pygmy hedgehogs worldwide. Selected new and emerging diseases occurring in these commonly reported groups are discussed in greater detail, focusing on Caparinia tripilis infestation and brain tumors. This article primarily discusses African pygmy hedgehogs, with some reference to European free-living hedgehogs.

Clinicopathologic Findings of Spontaneous Leukemia in 9 Pet African Hedgehogs (Atelerix Albiventris)

Previous reports of leukemia in hedgehogs are limited. We describe clinicopathologic features of leukemia in 9 hedgehogs, including eosinophilic leukemia (n = 3) and acute leukemia/leukemic phase of lymphoma (n = 6). All 3 hedgehogs with eosinophilic leukemia were older than 2 years of age; in contrast, 4 of 6 cases of acute leukemia/lymphoma were <2 years old. Hedgehogs presented for non-specific clinical signs of anorexia and lethargy. On hematologic testing, hedgehogs with eosinophilic leukemia had a marked leukocytosis, consisting mostly of eosinophilic precursors with fewer mature eosinophils, whereas there were 43–97% immature cells (blasts) in the blood of hedgehogs with acute leukemia/lymphoma. Anemia (n = 6) and/or thrombocytopenia (n = 6) were concurrent findings. Increased liver enzyme activities (alanine aminotransferase, alkaline phosphatase) and hypoalbuminemia were the common findings on biochemical panels. All cases of eosinophilic leukemia and 4 cases of acute leukemia/lymphoma died shortly after diagnosis (median 7 days, range 0–41 days), whereas 2 cases of acute leukemia/lymphoma lived for 94 or 101 days. Postmortem examination in 5 cases (1 eosinophilic leukemia, 4 acute leukemia/lymphoma) showed bone marrow infiltrates, confirming eosinophilic leukemia and acute leukemia in 1 and 3 cases, and bone marrow necrosis in 1 animal with acute leukemia/lymphoma. Immunohistochemical staining of bone marrow sections confirmed a T-cell acute leukemia in 1 case. Several hedgehogs had concurrent carcinomas. Hedgehogs suffer from eosinophilic leukemia and acute leukemia/lymphoma. However, classification of acute leukemia by lineage was not possible due to lack of hedgehog cross-reactive or species-specific reagents.

Lymphoma with Mott cell differentiation and validation of immunohistochemical lymphoid markers in an African pygmy hedgehog (Atelerix albiventris)

A 2-year-old female intact African pygmy hedgehog was presented for diagnostic investigation of a 2-month reduction in appetite, with weight loss and recent vomiting. Clinical examination revealed a large, firm mass originating from the left cranial abdomen. Ultrasound-guided fine-needle aspirates of the mass, liver, and mesenteric lymph nodes revealed a population of pleomorphic round cells, some of which contained variable numbers of round, clear vacuoles, consistent with a diagnosis of lymphoma with Mott cell differentiation. At postmortem examination, there was marked diffuse splenic enlargement, with infiltration by a soft tissue mass. There were multiple coalescing liver masses, kidney pallor, and mesenteric lymph node enlargements. On histologic examination, the spleen, lymph nodes, and masses in the liver were extensively infiltrated by proliferating lymphoid cells that had plasmacytoid and Mott cell differentiation. Cells with Mott cell morphology had an accumulation of periodic acid-Schiff-positive material in cytoplasmic inclusions and were positive for cytoplasmic nucleic acids when stained with methyl green pyronin. In the population of neoplastic lymphoid cells, a majority of cells expressed the transcription factor Pax5, which drives B-cell differentiation, and a minority expressed transcription factor IRF4/MUM-1, which drives plasma cell differentiation, indicating B-cell lymphoma with plasmacytoid differentiation.

Comparative aspects of mast cell neoplasia in animals and the role of KIT in prognosis and treatment

Mast cell neoplasia clinical presentation and biological behaviour vary considerably across mammalian species, ranging from a solitary benign mass to an aggressive systemic malignancy. Mutations in the KIT Proto‐Oncogene Receptor Tyrosine Kinase (KIT) gene are common molecular abnormalities involved in mast cell tumorigenesis. KIT mutations often occur in dog, cat and human neoplastic mast cells and result in altered Kit protein structure and function. In dogs, certain KIT mutations are associated with more malignant and lethal disease. In contrast, KIT mutations in feline and human mast cell neoplasms are not correlated with prognosis, but are of value in diagnosis and treatment planning in humans. KIT genetic abnormalities have not been well investigated in other species, although aberrant cytoplasmic Kit protein staining detected in neoplasms of the ferret, horse and cow resembles aberrant Kit staining patterns detected in neoplastic mast cells of dogs, cats and humans. Mutations within KIT are classified as either regulatory‐type or enzymatic pocket‐type mutations according to their location within the KIT Proto‐Oncogene. Mutations within the enzymatic pocket domain confer tumour resistance to tyrosine kinase inhibitors (TKIs). Hence, knowledge of tumour KIT mutation status adds valuable information for optimizing patient treatment strategies. The use of TKIs in combination with conventional chemotherapeutics has opened a new treatment avenue for patients unresponsive to existing drugs. This review highlights the similarities and differences of mast cell neoplasia in mammals with a special focus on the involvement of KIT in the canine and feline forms in comparison to human mast cell neoplasia.

Stromal-type Nephroblastoma with or without Anaplasia in Two Hedgehogs (Atelerix albiventris)

We describe the clinical and histological characteristics of stromal-type nephroblastomas that developed in two hedgehogs (Atelerix albiventris). In case 1, the tumour was composed of a proliferation of anaplastic stromal cells with ductal structures resembling the epithelium of nephroblastoma. In case 2, spindle-shaped cells that were somewhat larger than nephroblasts were frequently seen surrounding the cell cluster, and there was proliferation of stromal cells with collagen fibres at the periphery. Immunohistochemically, the tumour cells labelled weakly to strongly for the nephroblast marker Wilms' tumour-1 and were positive for Ki67 with rates of 5% and 10% for cases 1 and 2, respectively. Based on the above, the diagnosis was of stromal-type nephroblastoma with anaplasia in case 1 and without anaplasia in case 2. Our findings suggest that stromal-type nephroblastomas arise in adult hedgehogs and are clinically benign, and that histological anaplasia does not affect the prognosis.

Endometrial polyp with chronic endometritis in an African pygmy hedgehog (Atalerix albiventris) – a case report

An African pygmy hedgehog (Atalerix albiventris) (APH) was admitted to the clinic with a history of vaginal bleeding. Examination showed poor clinical status of the patient based on haemogram values. The ultrasound showed an enlarged uterus filled with an anechoic content without the presence of free abdominal fluid. Ovariohysterectomy was performed under general inhalation anaesthesia. Histopathology examination was performed on tissue samples of the uterus with the final diagnosis of an endometrial polyp with endometrial cystic hyperplasia and chronic endometritis. In regard to the diagnostic findings, therapeutic option and postoperative care performed in this case, it is important to emphasize the fact that an early diagnosis of a reproductive disease contributes to proper treatment and a positive outcome. The endometrial polyp with cystic endometrial hyperplasia and chronic endometritis should be added to the list of differential diagnoses in cases where neoplasia of the reproductive system is suspected in an APH.

Oral masses in African pygmy hedgehogs

African pygmy hedgehogs (Atelerix albiventris) frequently develop oral neoplasms, and most of these neoplasms are malignant. We characterized oral masses detected in hedgehogs at clinical examination. During a 1-y period, we diagnosed oral cavity masses in 27 privately owned hedgehogs; 16 were female and 11 were male, with ages of 2-7 y (mean: 4.3 y). Eight masses were non-neoplastic and were diagnosed as gingival hyperplasia (GH). Nineteen masses were neoplastic, of which 17 were squamous cell carcinomas (SCCs) and 2 were mesenchymal tumors (1 spindle cell tumor of probable neural origin, and 1 hemangiosarcoma). The GHs were noninvasive, exophytic, and did not recur after surgical excision. The SCCs were highly invasive tumors that induced facial deformation and were located in the caudal portion of the oral cavity, with 12 of them arising from the right-caudal maxilla. Thus, clinical signs, growth pattern, and anatomic location can be used to suspect a diagnosis of SCC among the other possible diagnoses, such as GH, in this location. However, histopathology is necessary for confirmation. Also, hemangiosarcoma should be considered among the differential diagnoses.

Clinical management and outcome of four-toed hedgehogs (Atelerix albiventris) with histiocytic sarcoma

Four-toed hedgehogs presented bloody stool and loss of appetite. Integumental masses were observed in two of the four cases. Intraabdominal masses were observed on radiographs and ultrasonography in the remaining two cases. The masses were surgically removed from all four cases. All samples were histologically and immunohistochemically consistent with histiocytic sarcoma (HS). At the time of surgery, 3 of 4 cases had grossly recognized metastatic/disseminated lesions. Survival time was 48 days, 64 days, and 113 days, respectively, and the remaining case is currently alive (at Day 207). The present report describes the clinical management and outcome of hedgehogs that were diagnosed with HS.

Electrochemotherapy palliation of an oral squamous cell carcinoma in an African hedgehog (Atelerix albiventris)

A five-year-old female African hedgehog (Atelerix albiventris) was referred for a one month growing oral mass. The hedgehog was quiet, alert and responsive, with a 1.00 × 1.50 cm ulcerated lesion on the mandible. The patient was staged with total body radiographs, hematological and biochemical analyses and the mass was biopsied under anesthesia. The excised tissue was reported to be a squamous cell carcinoma. At this time, due to the extension of the mass, a surgical excision was not a therapeutic option and the tumor was palliated with electrochemotherapy (ECT). Monthly sessions of ECT were performed using intra-lesional bleomycin injection followed by trains of biphasic electric pulses. The treatment was well tolerated and the patient remained in partial remission for five months until tumor progression. At that time the pet was euthanized. The ECT resulted in improved local control and should be considered as a possible adjuvant treatment in exotic pets with advanced tumors.

Pleomorphic adenoma of the mandibular salivary gland in a captive African pygmy hedgehog (Atelerix albiventris)

A 3.9-year-old female African pygmy hedgehog (Atelerix albiventris) had a firm, tan-colored mass with an uneven surface arising from the mandibular salivary gland. A histopathologic examination revealed that the mass was composed of neoplastic proliferation of epithelial and spindle cells. The neoplastic spindle cells showed positive for vimentin, smooth muscle actin, calponin and cytokeratin 14 and, negative for cytokeratin 19, suggesting that spindle cells were derived from myoepithelial cells. Based on the histological findings and immunohistochemistry results, the mass was diagnosed as pleomorphic adenoma. Pleomorphic adenoma is the most common benign tumor found in human salivary glands, but it is rare in animals. To the best of our knowledge, this is the first report of pleomorphic adenoma in hedgehogs.

Primary central nervous system neoplasms in African hedgehogs

In this retrospective study, we describe the clinicopathologic and immunohistochemical findings in a series of primary central nervous system (CNS) neoplasms in African hedgehogs ( Atelerix albiventris). Twelve CNS neoplasms were found among 762 African hedgehog submissions (1.6%) to a private diagnostic laboratory in an 18-y period. The median age of affected hedgehogs was 3.5 y. No sex predilection was found. Hindlimb paresis, weakness, and ataxia were the most commonly reported clinical signs. Gangliogliomas ( n = 6) and astrocytomas ( n = 5) were the most commonly observed neoplasms; one oligodendroglioma was found. Gangliogliomas were found in the cerebellar white matter (2 of 6), brainstem (4 of 6), cervical spinal cord (1 of 6), and frontal lobe (1 of 6); one metastasized to the tongue. Gangliogliomas were immunoreactive for neurofilament protein (NFP), glial fibrillary acidic protein (GFAP), S100, and CD34. All astrocytomas were gemistocytic, located in the cerebrum, and none of these neoplasms metastasized. Astrocytomas were positive for GFAP, S100, and CD34, but negative for NFP. The oligodendroglioma was located in the cerebrum, and was positive for S100, but negative for GFAP and NFP.

A retrospective study of disease incidence in African pygmy hedgehogs (Atelerix albiventris)

The African pygmy hedgehog (Atelerix albiventris) is becoming a popular pet in Japan. The aim of this study was to determine the incidence of various diseases in African pygmy hedgehogs. We histologically investigated 105 samples from 100 privately-owned pet African pygmy hedgehogs that were submitted to two laboratories (North Lab and Patho Labo) between 2012 and 2017. Tissues submitted for this study were taken from female reproductive organs (33 cases; 31.43%), skin (20 cases; 19.05%), and the oral mucosa (19 cases; 18.1%). The most common histological diagnoses included endometrial stromal nodules identified as benign uterine neoplasia (14 cases; 13.33%); endometrial polyps identified as non-neoplastic polyps (7 cases; 6.67%), gingival hyperplasia and chronic suppurative inflammation in the oral mucosa (11 cases; 10.48%), fibrosarcomas in the skin (8 cases; 7.62%), and mammary tumors (8 cases; 7.62%). In this study, lymphoma and oral squamous cell carcinoma were less common than in the previous reports. The present study revealed the disease prevalence in captive African pygmy hedghogs that were histopathologically examined.

From humans to hydra: patterns of cancer across the tree of life

Cancer is a disease of multicellularity; it originates when cells become dysregulated due to mutations and grow out of control, invading other tissues and provoking discomfort, disability, and eventually death. Human life expectancy has greatly increased in the last two centuries, and consequently so has the incidence of cancer. However, how cancer patterns in humans compare to those of other species remains largely unknown. In this review, we search for clues about cancer and its evolutionary underpinnings across the tree of life. We discuss data from a wide range of species, drawing comparisons with humans when adequate, and interpret our findings from an evolutionary perspective. We conclude that certain cancers are uniquely common in humans, such as lung, prostate, and testicular cancer; while others are common across many species. Lymphomas appear in almost every animal analysed, including in young animals, which may be related to pathogens imposing selection on the immune system. Cancers unique to humans may be due to our modern environment or may be evolutionary accidents: random events in the evolution of our species. Finally, we find that cancer‐resistant animals such as whales and mole‐rats have evolved cellular mechanisms that help them avoid neoplasia, and we argue that there are multiple natural routes to cancer resistance.

Oligodendrogliom mit neuronaler Differenzierung bei einem 8 Monate alten Afrikanischen Weißbauchigel (Atelerix albiventris)

Ein 8 Monate alter, männlicher Afrikanischer Weißbauchigel zeigte klinisch einen schwankenden Gang, Anurie, Inappetenz und Apathie, woraufhin die Verdachtsdiagnose Wobbly Hedgehog Syndrome gestellt wurde. Nach Exazerbation wurde der Igel euthanasiert. Der histologisch im Großhirn nachgewiesene Tumor bestand überwiegend aus mittelgroßen, ovoiden Zellen und einer in geringerer Zahl vorhandenen spindelzelligen Zellpopulation. Im Tumor fanden sich Neuropil-Inseln und extrazelluläres myxoides Material. Immunhistochemisch exprimierten die Tumorzellen sowohl oligodendrogliale (neuritic outgrowth inhibitor, Nogo-A; oligodendrocyte transcription factor, Olig-2) als auch neuronale (neuronenspezifische Enolase, NSE; microtubuleassociated protein-2a, MAP-2a; Synaptophysin) Zellmarker. Anhand der Befunde wurde die Diagnose eines Oligodendroglioms mit neuronaler Differenzierung gestellt, wobei es sich um einen bei Weißbauch - igeln bisher nicht beschriebenen Hirntumor handelt. Die bei der Obduktion festgestellte hochgradige Füllung und Dilatation der Harnblase wurde vermutlich durch eine tumorbedingte zentrale Blockade des Blasenentleerungszentrums hervorgerufen. Auch bei jungen Igeln sollte im Fall neurologischer Symptome an einen primären Gehirntumor gedacht werden. Differenzialdiagnostisch sind entzündlich-infektiöse (Tollwut, Herpes, Baylisaskariose), degenerative (Kardiomyopathie, Bandscheibenerkrankung), traumatische, alimentäre (Vitamin-B-Mangel) und metabolisch-toxische (Hitze-Kälte-Starre, hepatische Enzephalopathie) Noxen auszuschließen.

Spontaneous multicentric soft tissue sarcoma in a captive African pygmy hedgehog (Atelerix albiventris): case report and literature review

This report describes the clinical, macroscopic, histopathological and immunohistochemical features of a spontaneous multicentric extraskeletal sarcoma in an adult male African hedgehog (Atelerix albiventris). It also provides a succinct up-to-date review on neoplasia in this species. On autopsy examination, main gross findings included a moderately demarcated cranial mass and a multilobulated, caudal intra-abdominal mass. The cranial mass had perforated the underlying temporal and occipital bones and had extended into the cranial vault and was compressing the surface of the cerebellum and cerebrum. Histologic, histochemical and immunohistochemical analyses supported a diagnosis of multicentric poorly differentiated spindle cell sarcoma with fibrosarcomatous, storiform and myxoid foci. The high incidence of neoplasia and cross similarities renders the African hedgehog a suitable species for comparative pathology studies.

Oral Squamous Cell Carcinoma in Three Related Kowari (Dasyuroides byrnei)

We report three kowari (Dasyuroides byrnei) with squamous cell carcinoma affecting the gingiva. These cases occurred in rapid succession in a related group of individuals of similar age, suggesting a familial tendency to this condition and a typical age of presentation. Other conditions affecting the oral cavity can mimic the appearance of oral squamous cell carcinoma in this species, and so knowledge of this condition can assist the veterinarian in making rapid decisions regarding prognosis and improving the welfare of these animals.

Eosinophilic leukemia in three African pygmy hedgehogs (Atelerix albiventris) and validation of Luna stain

Neoplasia is usually encountered in the African pygmy hedgehog at a mean age of 3.5 y, and malignancy is common. Myelogenous leukemias are rarely reported in hedgehogs. We describe 3 cases of eosinophilic leukemia in adult, middle-aged (mean age: 2.3 y) hedgehogs, for which prognosis appears grave. In 1 case, attempted treatment was unsuccessful, and in all 3 cases, the disease course was rapid and all died soon after diagnosis. Blood smear evaluation, along with complete blood count, was critical in making the diagnosis in all cases. Luna stain was validated and used to better visualize eosinophils in cytologic and histologic sections. Electron microscopy confirmed the presence of specific granules in hedgehog eosinophils.

Common Emergencies in Small Rodents, Hedgehogs, and Sugar Gliders

Small exotic mammal pets such as rats, mice, hamsters, gerbils, degus, hedgehogs, and sugar gliders are becoming more popular. Because these animals are prone to a variety of health problems, and require specialized husbandry care to remain healthy, they may present to emergency hospitals in critical condition. This article provides a basic overview of common emergency presentations of these species.

Myxoma of the penis in an African pygmy hedgehog (Atelerix albiventris)

A penile tumor (4 × 2.5 × 1 cm) was surgically removed from an African pygmy hedgehog (Atelerix albiventris) aged 3 years and 5 months. The tumor was continuous with the dorsal fascia of the penile head. Histopathologically, tumor cells were pleomorphic (oval-, short spindle- and star-shaped cells) with low cell density. Abundant edematous stroma was weakly positive for Alcian blue staining and positive for colloidal iron reaction. Tumor cells displayed no cellular atypia or karyokinesis. Tumor cell cytoplasm was positive for vimentin antibody, while cytoplasm and nuclei were positive for S-100 protein antibody. Tumor cell ultrastructure matched that of fibroblasts, and the rough endoplasmic reticulum was enlarged. The tumor was diagnosed as myxoma. This represents the first report of myxoma in a hedgehog.

CASE REPORT: ENDOMETRIAL STROMAL SARCOMA AND LIPOSARCOMA IN AN AFRICAN HEDGEHOG (Atelerix albiventris)

A 2-year-7-month-old female intact African hedgehog was presented with a subcutaneous mass around the right side of the neck as well as an intra-abdominal mass found during palpation. Surgical excision and exploratory laparotomy were performed. A uterine mass was identified during laparotomy and ovariohysterectomy was performed. The botryoid mass measured [Formula: see text][Formula: see text]cm and was located in the right uterine horn. It had a meat-like texture and was yellow-white and dark red in color. The removed subcutaneous mass measured [Formula: see text][Formula: see text]cm. The mass was well-encapsulated and had a yellow-white homogeneous texture on the cut surface. Histologically, the myometrium was invaded by neoplastic cells and the tissue boundaries were not obvious. Neoplastic cells were arranged in a whirling or intersecting pattern, with strong angiogenesis present. Vacuolated nuclei were round and oval to cigar shaped, with one to multiple nucleoli present. Immunohistochemistry revealed a positive reaction for CD10, but a negative reaction for smooth muscle actin (SMA) and desmin in the uterine neoplastic cells. Histologically, well-differentiated adipocytes with sheets of undifferentiated polygonal neoplastic cells, which were characterized by vacuolated nuclei with prominent multiple nucleoli, were found in the subcutaneous mass. Neoplastic cells of the subcutaneous mass were positively stained with antibodies of MDM2 and estrogen receptor (ER), but failed to give a positive result for vimentin because the cross-species interaction was insufficient. The definitive diagnosis was endometrial stromal sarcoma and liposarcoma in an African hedgehog.

Anatomy and Disorders of the Oral Cavity of Miscellaneous Exotic Companion Mammals

Unusual mammalian species such as the hedgehog, sugar glider, and miniature pig are encountered with increasing frequency in exotic companion medicine. Disease of the oral cavity can occur in any species; although occasionally encountered in exotic mammalian species, it is rarely described in the literature. Anatomy and dentition vary significantly; diagnosis and treatment are often extrapolated from that known in other species. The best-documented disease of the oral cavity in this group of species is oral neoplasia in the hedgehog.