Hamartoma affecting ampullary electroreceptors and epitheliotropic lymphoma in a captive electric eel Electrophorus varii.

Few reports are available describing lesions in captive electric eels Electrophorus spp. This report describes 2 types of cutaneous proliferative lesions (i.e. hamartoma and neoplasm) in a captive electric eel. Ampullary electroreceptor hamartomas appeared grossly as 2 discrete, smooth, pink, spherical, cutaneous masses measuring 6 and 18 mm in diameter. Histologically, hamartomas were composed of predominately spindle cells that were separated into lobules by a peripheral rim of polygonal cells. Spindle cells were arranged in vague streams and occasionally whorls within a myxomatous matrix. Polygonal cells arranged in variably sized trabeculae and cords within a pre-existing fibrovascular stroma surrounded the streams of spindle cells. Admixed with the polygonal cell population were multiple mucous glands and alarm cells, similar to those seen in normal regions of epidermis. Histochemical stains confirmed similar components in the normal ampullary electroreceptor as in the hamartomas. Lymphoma was also present, appearing grossly as patchy pitting, erythematous, and thickened areas of the skin affecting the entire animal. Lymphoma was diffusely infiltrating and expanding the epidermis, oral mucosa, and branchial mucosa up to 1.5 mm in thickness. It was composed of an unencapsulated, well-demarcated, moderately cellular neoplasm composed of lymphocytes arranged in small dense sheets and clusters that separated and effaced epidermal cells. This is the first report of lymphoma in an electric eel, and the first report of ampullary electroreceptor hamartoma in any animal species.

Dysplastic gangliocytoma of the cerebellum in a cat.

A 2.5-year-old cat presented with progressive ataxia and lethargy. Magnetic resonance imaging (MRI) showed enlargement of the cerebellum and herniation of cerebellar vermis. Postmortem examination confirmed the MRI findings, and histopathology showed numerous large dysplastic neurons populating and displacing the Purkinje cell layer and extending into the molecular and granular layers of the cerebellum. The lesion was diagnosed as dysplastic gangliocytoma of the cerebellum. In humans, this tumor is often associated with Cowden syndrome, a genetic disorder characterized by multiple hamartomas and an increased risk of developing certain neoplasms, known to be linked to a germline mutation of the phosphatase and tensin homolog (PTEN) gene. Reduction in PTEN nuclear and cytoplasmic immunohistochemical labeling of dysplastic neurons in this case suggested a possible PTEN mutation involved in the tumorigenesis. This report provides a detailed pathology description of the tumor and the use of neuronal and PTEN markers which will help guide pathologists presented with this rare condition in the future.

Locally extensive follicular hamartomas with concurrent follicular cysts and dermoid cysts on the head of a dog.

A 5-month-old, male intact Australian shepherd dog was presented with nodular lesions affecting the dorsal head. A locally diffuse form of follicular hamartomas, with concurrent dermoid cysts and follicular cysts, was diagnosed by histopathological examination. Complete surgical excision of the affected skin and closure with a subdermal plexus advancement flap led to long-term resolution.

Un berger australien mâle intact âgé de 5 mois a été présenté avec des lésions nodulaires affectant la face dorsale de la tête. Une forme localement diffuse d'hamartomes folliculaires, avec des kystes dermoïdes et des kystes folliculaires concomitants, a été diagnostiquée par examen histopathologique. L'éxérèse chirurgicale complète de la peau atteinte et la fermeture avec un lambeau d'avancement du plexus sous-cutané ont conduit à une résolution à long terme.

Un perro pastor australiano macho entero de 5 meses de edad se presentó con lesiones nodulares que afectaban el dorso de la cabeza. Mediante examen histopatológico se diagnosticó una forma localmente difusa de hamartomas foliculares, con quistes dermoides y quistes foliculares concurrentes. La escisión quirúrgica completa de la piel afectada y el cierre con una zona avanzada en colgajo del plexo subdérmico condujo a una resolución a largo plazo.

Multiple follicular abnormalities in a 1-year old cat consistent with basaloid follicular hamartomas.

BACKGROUND: In humans, basaloid follicular hamartomas are benign follicular tumours, that can be solitary or multiple, in which case they show autosomal dominant inheritance. HYPOTHESIS/OBJECTIVES: This study describes clinical and histopathological findings observed in a young cat, which could be consistent with basaloid follicular hamartomas. CASE DESCRIPTION: Multiple follicular abnormalities, consistent with cutaneous diffuse basaloid follicular hamartomas, were observed in skin samples from a one-year old neutered domestic short hair cat. Clinical signs were diffuse symmetrical alopecia with exaggerated skin markings (ventral abdomen, thorax and medial aspects of the limbs) and intense follicular-centred thickening (face and feet). Microscopic lesions were characterised by multiple proliferative follicular abnormalities in all samples. The epidermis showed a very irregular surface with the follicles filled with variably pigmented keratin. The epithelial walls of the follicles had multiple small hyperplastic basaloid cells foci. In the superficial dermis under the epidermis and around the follicles, fibroblastic spindle-shaped mesenchymal cells with a homogeneous moderate density were present in the collagenous connective tissue. The interfollicular epidermis was also abnormal with multiple small proliferating trichoblastic foci originating from the basal layer. RNAscope testing for feline papillomavirus was negative. CONCLUSIONS AND CLINICAL RELEVANCE: This case report provides the first evidence of clinical and histopathological findings of multiple follicular abnormalities, consistent with cutaneous diffuse basaloid follicular hamartomas in a cat.

De multiples anomalies folliculaires, compatibles avec des hamartomes folliculaires basaloïdes diffus cutanés, ont été observées dans des échantillons de peau d'un chat domestique à poils courts castré âgé d'un an. Les signes cliniques étaient une alopécie diffuse symétrique avec des marques cutanées exagérées (abdomen ventral, thorax et face médiale des membres) et un épaississement folliculaire intense (face et pieds).

Múltiplas anormalidades foliculares, consistentes com hamartomas cutâneos foliculares basaloides difusos, foram observadas em amostras de pele de um gato doméstico de pelo curto castrado de um ano de idade. Os sinais clínicos foram alopecia simétrica difusa com marcações cutâneas exuberantes (abdômen, tórax e aspecto medial dos membros) e espessamento folicular central intenso (face e patas).

Se observaron múltiples anomalías foliculares, consistentes con hamartomas foliculares basaloides difusos cutáneos, en muestras de piel de un gato doméstico de pelo corto castrado de 1 año. Los signos clínicos fueron alopecia simétrica difusa con marcas cutáneas exageradas (abdomen ventral, tórax y cara medial de las extremidades) e intenso engrosamiento de la piel centrado en los folículos (cara y pies).

Linear arrector pili muscle hamartoma on the tail of a sphynx cat.

Arrector pili muscle (APM) hamartoma is reported in humans and dogs. We describe a linear APM hamartoma in a sphynx cat. The lesion was characterized by multiple nodules distributed linearly along the tail, made of randomly arranged hypertrophic smooth muscles, the size of which tended to wax-and-wane during a one year follow-up.

L'hamartome du muscle arrecteur du poil (APM) est décrit chez l'homme et chez le chien. Nous décrivons un hamartome APM linéaire chez un chat sphynx. La lésion était caractérisée par de multiples nodules répartis en ligne sur la queue, composés de fibres musculaires lisses hypertrophiques désordonnées, dont la taille a évolué par poussée au cours d'une période de suivi d'un an.

El hamartoma del músculo erector piloso(APM) ha sido descrito en humanos y en perros. Describimos un hamartoma APM lineal en un gato esfinge. La lesión se caracterizó por múltiples nódulos distribuidos linealmente a lo largo de la cola, compuestos de músculos lisos hipertróficos dispuestos al azar, cuyo tamaño tendía a fluctuar durante un año de seguimiento.

O hamartoma do músculo eretor do pelo (MEP) é relatado em humanos e cães. Nós descrevemos um hamartoma linear em um gato sphynx. A lesão foi caracterizada por múltiplos nódulos distribuídos linearmente ao longo da cauda, constituídos por músculos lisos hipertróficos dispostos aleatoriamente, cujo tamanho tendia a aumentar e diminuir ao longo do acompanhamento de um ano.

Clinical, MRI, and Histopathological Features of Hypothalamic Neuronal Hamartoma in a Young Vizsla.

Human hypothalamic neuronal hamartomas are rare, nonprogressive, congenital malformations of the hypothalamus that do not expand or metastasize to other locations. A 1 yr old female vizsla was presented for progressive intracranial multifocal neurological signs present since adoption at 3 mo of age. MRI of the brain showed an ill-defined, intra-axial, space-occupying, nonenhancing lesion located in the ventral middle cranial fossa. Histopathological examination was consistent with hypothalamic neuronal hamartoma. This is the first report describing clinical, imaging, and histopathological features of a hypothalamic neuronal hamartoma in a dog. These findings are compared with their human counterparts.

An Angiomyomatous Hamartoma With Features of Vascular Transformation of Sinuses in the Mediastinal Lymph Node of a Beagle Dog.

Two similar benign, nonneoplastic vascular lesions have been described in the lymph nodes of humans and animals: angiomyomatous hamartoma (AMH), which is characterized by the replacement of lymphoid tissue by blood vessels, smooth muscle, and fibrous tissue, and vascular transformation of sinuses (VTS), which is considered a reactive transformation of lymph node sinuses into capillary-like vascular channels. We hereby report a lesion with features common to both lesions in the mediastinal lymph nodes of a 1-year-old beagle dog in a 1-month toxicity study. Grossly, enlargement and red discoloration were observed, while microscopically, the lesion was characterized by effacement of the lymph node parenchyma with replacement by mature blood vessels, smooth muscle, and fibrous tissue, associated with lymphoid atrophy, which is consistent with AMH. However, multifocal areas of anastomosing or plexiform capillary-like channels lined by normal to slightly plump endothelium, similar to those described for VTS, were also present. Immunohistochemistry analysis revealed abundant positive staining for smooth muscle actin and endothelial cells (von Willebrand factor/factor VIII) and the absence of proliferation (Ki67). In conclusion, these lesions most likely represent a mixture of both AMH and VTS.

Odontomas in Frogs.

Odontomas are variably differentiated, hamartoma-like proliferations of odontogenic epithelium, pulp ectomesenchyme (odontoblasts), and dental matrix. Frogs are polyphyodont and homodont. Their teeth also differ from mammals in that they are restricted to the upper jaw in adults and lack a periodontal ligament and cementum, attaching directly to the underlying bone. Odontomas were identified in an African clawed frog (Xenopus laevis), a false tomato frog (Dyscophus guineti), and a tomato frog of unknown species (Dyscophus sp.). All of the examined odontomas were composed of numerous tooth-like structures comprising an arc of dentinal matrix lined on the convex surface by ameloblasts and on the concave surface by odontoblasts. Masson's trichrome and immunohistochemistry with pan-cytokeratin supported these findings. The pathogenesis of these lesions may be displacement of the dental lamina, which has been shown in research studies to lead to de novo proliferation of dental elements in frogs.

Intranodal Angiomyomatous Hamartoma in a Cynomolgus Monkey.

We describe here an angiomyomatous hamartoma in the right axillary lymph node of a three-year-old male cynomolgus monkey ( Macaca fascicularis), used as a control subject in a short-term toxicity study. This is a very rare lesion that has been reported almost exclusively in inguinal lymph nodes, and to date only in human beings. In the present case, light microscopy revealed partial replacement of the lymph node parenchyma by a disorganized, irregular vascular network, sparsely distributed smooth muscle cells, and a fibro-adipocytic stroma. This was considered to be fortuitous given the age of the animal, with no clinical or toxicological significance. To the best of our knowledge, this is the first report of an intranodal angiomyomatous hamartoma in a nonhuman animal species.

A perineal cystic hamartoma causing constipation in an intact female Irish water spaniel.

A perineal fluid-filled structure was discovered in a 6-year-old intact female Irish water spaniel suffering from intermittent constipation. Diagnostic tests revealed the structure was immediately caudal to the vagina and compatible with a cyst. Surgical excision was required for resolution of clinical signs. Histology confirmed the structure was a cyst. The exact origin is unknown; however, the variety of lining epithelia, including sections with mucin production, and a well-differentiated smooth muscle layer, were most consistent with development from the lower hindgut or urogenital sinus during embryonic growth. The histologic and anatomical similarities with human retrorectal cystic hamartomas were key in establishing the diagnosis of a perineal cystic hamartoma. Following removal, constipation resolved, and the cyst did not recur.

Hamartome kystique périnéal causant de la constipation chez une femelle intacte de race épagneul d'eau irlandais. Une structure périnéale remplie de liquide fut découverte chez une chienne intacte de race épagneul d'eau irlandais âgée de 6 ans souffrant de constipation intermittente. Les tests diagnostiques ont révélé que la structure était immédiatement caudale au vagin et était compatible avec un kyste. L'excision chirurgicale était requise pour la résolution des signes cliniques. L'histologie confirma que la structure était un kyste. L'origine exacte est inconnue; toutefois, la diversité de l'épithélium de couverture, incluant des sections avec production de mucine, et une couche bien différenciée de muscle lisse, étaient plus cohérentes avec un développement à partir du tractus digestif postérieur ou du sinus urogénital lors de la croissance embryonnaire. Les similarités histologique et anatomique avec l'hamartome rétro-rectal humain étaient critiques pour établir le diagnostic d'hamartome kystique périnéal. À la suite du retrait, la constipation s'est résolue, et il n'y a pas eu de récurrence du kyste.(Traduit par Dr Serge Messier).

IMAGING DIAGNOSIS-IMAGING AND HISTOPATHOLOGIC CHARACTERISTICS OF A VERTEBRAL HAMARTOMA IN A CAT.

A 9-month-old domestic shorthair cat had progressive ambulatory paraparesis, proprioceptive ataxia, and thoracolumbar hyperesthesia. An extradural mass affecting the left pedicle and lamina of the second lumbar vertebra (L2) causing marked spinal cord impingement was identified in magnetic resonance (MR) images. The mass was predominantly calcified in computed tomographic (CT) images. A hemilaminectomy was performed to resect the mass. Clinical signs were greatly improved at 12-month follow-up. The histopathologic diagnosis was vascular hamartoma. To our knowledge, this is the first report describing the MR characteristics of a vascular hamartoma associated with the vertebral column.

Nasal tissue-derived hamartoma in the maxillary gingiva of a calf.

BACKGROUND: All of oral hamartomas has been previously found in mandibular gingiva in younger calves, and were histologically diagnosed as a vascular hamartoma. This is the first case report describing a calf with a mass in the maxillary gingiva that was histologically diagnosed as a nasal tissue-derived hamartoma. CASE PRESENTATION: A 13-day-old male Holstein calf presented with a horn-like mass in the left rostral maxillary gingiva. Surgical removal revealed that the mass had a dual structure composed of cartilaginous and soft tissues and extended deeply toward the nasal cavity. Excised tissues mainly consisted of two types of mature cells without mitotic figures and atypia: 1) the cartilage-like structures consisted of an island and a meandering massive focus of mature cartilaginous tissues, and 2) tubular structures consisting of stratified ciliated mucosal columnar cells with gland-like structures and aggregated goblet cells. The mass was diagnosed as a nasal tissue-derived hamartoma because these two types of structures were histologically identical to nasal structures. The present case had no recurrence at 1 year after surgery. CONCLUSIONS: To our knowledge, this is the first description of the calf with nasal tissue-derived hamartoma in the maxillary gingiva.

Nasal Cavity Masses Resembling Chondro-osseous Respiratory Epithelial Adenomatoid Hamartomas in 3 Dogs.

Chondro-osseous respiratory epithelial adenomatoid hamartomas (COREAHs) are rare tumors in the nasal cavity of people, which have not been described in other species. COREAHs in people are minimally invasive and rarely recur following excision. Histologically, these tumors are composed of disorganized, mature, nasal turbinate tissue that is organized into polypoid growths. These growths are lined by respiratory epithelium, contain glandular elements, and are organized around central cores of chondro-osseous matrix. This report describes 3 cases of dogs with nasal tumors that have histomorphology similar to that of COREAH in people. The tumors were all identified within the nasal cavity and were associated with regional bony lysis of the turbinates and surrounding skull bones, a feature that has not been reported in COREAH in people. There was no evidence of metastasis or extension beyond the nasal cavity in any of the 3 cases.

Spinal Cord Hamartomatous Myelodysplasia in 2 Horses With Clinical Neurologic Deficits.

Two horses euthanized for neurologic deficits were diagnosed with hamartomatous myelodysplasia of the spinal cord. One was a 5-week-old Holsteiner colt exhibiting spasms of muscle rigidity in the extensor muscles of the limbs and epaxial muscles, and the other was a 3-year-old Thoroughbred colt exhibiting progressive ataxia and hypermetria in the pelvic limbs. Each had focal disorganization of the white and gray matter of the spinal cord forming a mass interspersed with neurons, glial cells, and disoriented axon bundles. In the Holsteiner colt, the mass was at the level of C5 and included islands of meningeal tissue contiguous with the leptomeninges. The mass occluded the central canal forming hydromyelia cranial to the occlusion. In the Thoroughbred colt, the mass was at the level of L1 on the dorsal periphery of the spinal cord and did not involve the central canal.

Cecal vascular hamartoma causing recurrent colic in an Arabian mare.

A 5-year-old mare was treated for recurrent colic and weight loss by surgical removal of an intraluminal cecal mass. Microscopic examination revealed vascular hamartoma. A 6-month follow-up showed an improvement in the general condition of the mare. Vascular hamartoma should be one of the differential diagnoses for weight loss and colic.

Coliques récurrentes causées par un hamartome vasculaire caecal chez une jument Arabe. Une jument de 5 ans a été traitée pour coliques récurrentes et perte de poids par exérèse chirurgicale d'une masse caecale intraluminale. L'examen microscopique a révélé un hamartome vasculaire. Un suivi de 6 mois a montré une amélioration de l'état général de la jument. L'hamartome vasculaire doit faire partie du diagnostic différentiel de l'amaigrissement et des coliques.(Traduit par les auteurs).

Scrotal tumors in dogs: a retrospective study of 676 cases (1986-2010).

The objective of this study was to determine common tumor types that occur on the canine scrotum in relation to other cutaneous locations and to identify potential risk factors for specific scrotal tumor development. A retrospective study was conducted and the database of pathology reports from the Surgical Pathology Service of the Department of Pathology and Toxicology, School of Veterinary Medicine, University of Pennsylvania from 1986 to 2010 was searched for canine neoplastic scrotal and non-scrotal cutaneous lesions. Neoplastic lesions were evaluated based on diagnosis, breed, age, and number and location of tumors (scrotal versus non-scrotal cutaneous). Mast cell tumor, melanocytoma, malignant melanoma, vascular hamartoma, hemangiosarcoma, hemangioma, and cutaneous histiocytoma were the most common tumor types identified on the canine scrotum. Breed predispositions and mean age at diagnosis were identified for each tumor type and should be considered when planning surgical excision of a canine scrotal tumor.

Tumeurs scrotales chez les chiens : étude rétrospective de 676 cas (1986­2010). Cette étude avait pour objectif de déterminer les types communs de tumeurs qui se produisent sur le scrotum canin par rapport à d'autres endroits cutanés et d'identifier les facteurs de risque potentiels pour le développement de tumeurs scrotales spécifiques. Une étude rétrospective a été réalisée et une recherche a été effectuée dans la base de données des rapports de pathologie du Service de pathologie chirurgicale du Département de pathologie et de toxicologie de l'École de médecine vétérinaire de l'Université de la Pennsylvanie de 1986 à 2010 pour les lésions scrotales néoplasiques et les lésions cutanées non scrotales canines. Les lésions néoplasiques ont été évaluées en fonction du diagnostic, de la race, de l'âge ainsi que du nombre et de l'emplacement des tumeurs (scrotales par opposition à cutanées non scrotales). Les tumeurs à mastocytes, les mélanocytomes, les mélanomes malins, les hamartomes vasculaires, les hémangiosarcomes, les hémangiomes et les histiocytomes cutanés étaient les types les plus communs de tumeurs identifiées sur le scrotum canin. Les prédispositions des races et l'âge moyen lors du diagnostic ont été identifiés pour chaque type de tumeur et devraient être considérés lors de la planification de l'excision chirurgicale d'une tumeur scrotale canine.(Traduit par Isabelle Vallières).

Dorsal rhinotomy in a dog with a chondro-osseous respiratory epithelial adenomatoid hamartoma: a case report.

OBJECTIVE: To describe the clinical presentation, novel surgical approach, and outcome of a dog diagnosed with chondro-osseous respiratory epithelial adenomatoid hamartoma (COREAH). ANIMAL: 5-year-old castrated male Yorkshire Terrier. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: The dog was presented with chronic upper respiratory noise, congestion, facial swelling, ocular discharge, and an abscess on the nasal bridge. Two CT scans were performed 4 months apart. The CT scans yielded similar results: cyst-like nasal masses with severely destructive bilateral rhinitis with extensive polyostotic bony lysis. A dorsal rhinotomy with a turbinectomy and debridement of the nasal cavity were performed. A poorly defined but extensive lesion was found occupying the entirety of the left frontal sinus as well as the nasal cavity. TREATMENT AND OUTCOME: Histopathology revealed a mass consistent with COREAH. The dog recovered well from surgery, except for self-limiting subcutaneous emphysema, and 3 weeks postoperatively was reportedly doing well, with mild nasal discharge. Stridor, nasal discharge, and sneezing episodes were reported postoperatively; however, these were improved. At 18 months postoperatively, the dog died from uncontrolled seizures while hospitalized for suspected acute hemorrhagic diarrhea syndrome at a different hospital. CLINICAL RELEVANCE: COREAH should be considered a potential cause of destructive bilateral rhinitis and bony lysis in dogs. Dorsal rhinotomy can be a surgical treatment for dogs with possible COREAH with acceptable outcome, though complete remission of clinical signs may not be achieved. This is the first clinical description of COREAH in a dog.

Vascular hamartoma in the uterus of a female Sprague-Dawley rat with an episode of vaginal bleeding.

An annular, reddened lesion with mild serosal hemorrhage and no tumorous mass formation was detected in the right uterine horn of a 37-week-old female Sprague-Dawley rat that had postpubertal vaginal bleeding. Histological examination revealed prominent proliferation of the endometrium, which occupied the uterine lumen. There were numerous aberrant vascular spaces filled with erythrocytes, proliferation of stromal cells, and inflammatory infiltrates including hemosiderin-laden macrophages in the endometrium. These vasculatures extended into the myometrium, and in a transverse section of the lesion, they were mostly distributed throughout the circumference of the uterus. They were irregular in shape and interconnected, forming a large vascular sinus and anastomosing reticular channels. In the area with serosal hemorrhage, the muscular layer covering the large irregular vascular space had undergone degeneration and necrosis. The lining cells of the vasculatures were often plump, and they protruded into the lumen and were arranged in a tombstone or hobnail manner. Immunostaining revealed that these cells were positive for von Willebrand factor and CD34. The aberrant vasculatures were not accompanied by pericytes or muscular layer, although a discontinuous muscular wall was present around some of them. From these results, the uterine lesion was diagnosed as a vascular hamartoma.

Pharyngeal odontoma in an adult walleye (Sander vitreus).

An adult walleye (Sander vitreus) was submitted to Cornell University for evaluation of a hard pale-tan pharyngeal mass attached to the gill arches. Dozens of hard white conical structures radiated from the surface. Microscopically, conical structures were identified as denticles and rested on plates of dysplastic orthodentine, cementum, and acellular bone. A diagnosis of compound odontoma was made based upon the presence of proliferative epithelial and mesenchymal odontogenic tissues that recapitulated tooth structures normally present on gill rakers. Odontomas are classified as hamartomas and typically develop in immature diphyodont mammals. The pharyngeal location and lifelong regeneration of teeth in fish, however, both qualify the present diagnosis in the pharyngeal region of an adult teleost. Ontogenic and morphologic differences between mammalian and piscine dentition and differentials for tooth-bearing tumors in fish are presented within the context of a developmental anomaly.