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.

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.

Bile duct hamartoma in a dog

An 11-year-old female Collie presented with a significantly increased abdominal circumference. Computed tomography of the abdomen revealed that the left lateral lobe of the liver contained a large mass, which was excised via laparotomy. Histologically, many small, dilated, cystic luminal structures were anastomosed and connected to a net-like structure. Immunohistochemistry revealed cytokeratin 19-immunopositive areas, representing bile duct structures in the cystic lumen. Based on these results, the tumour was diagnosed as a bile duct hamartoma. To our knowledge, this is the first report of a bile duct hamartoma in a dog.

Unilateral vascular hamartomas of the vaginal tunic in a dog

A 12-y-old, male Dachshund was presented for elective orchiectomy. The testes were of normal size. The left testis had numerous dark-red, blood clot-like foci within the vaginal tunic over the pampiniform plexus, epididymis, and testis. Histologically, the red foci were limited to the vaginal tunic and consisted of disorderly growing, variably sized, thin-walled blood vessels lined by a single layer of endothelial cells without mitoses and supported by a thin layer of pericytes. The blood vessels were distended by erythrocytes without thrombus formation. Endothelial cells had cytoplasmic immunolabeling for CD31; pericytes had strong cytoplasmic immunolabeling for α-smooth muscle actin. Our case of subclinical unilateral vascular hamartomas of the vaginal tunic in a dog has not been reported previously in domestic animals or humans, to our knowledge.

Lateral rhinotomy and coblation for treatment of a nasal hamartoma in a dog

CASE DESCRIPTION

A 4-year-old spayed female French Bulldog was referred for treatment of a suspected right-sided nasal angiofibroma associated with a 4-month history of unilateral nasal discharge and stertor.

CLINICAL FINDINGS

The dog appeared healthy other than right-sided mucoid debris and decreased airflow through the right naris. The dog was anesthetized, and a large intranasal mass was observed obstructing the right nasal passage and abutting the nasal septum.

TREATMENT AND OUTCOME

A lateral rhinotomy was performed, and rigid endoscopes (0° and 30°) were used to examine the right nasal cavity. The mass filled the anterior aspect of the nasal cavity and involved a portion of the nasal turbinates with some erosion. A coblation unit was used to ablate tumor tissue laterally to remove the tumor in piecemeal fashion. Recovery was routine with only minor epistaxis after surgery, and the dog was discharged the next day. Eight months after surgery, follow-up CT revealed right-sided nasal turbinate and conchal atrophy consistent with prior mass ablation. No macroscopic recurrence was detected, and the owners reported only rare, clear rhinorrhea.

CLINICAL RELEVANCE

Findings suggested that coblation may be an alternative to radiation therapy for vascular tumors with minimal invasion and low metastatic potential.

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.

Use of a frameless computed tomography-guided stereotactic biopsy system for nasal biopsy in five dogs

CASE DESCRIPTION

5 dogs (median age, 9 years; median body weight, 31 kg [68.2 lb]) with undefined nasal masses were examined after undergoing CT of the head and nasal biopsy via a rostral rhinoscopic or unaided (blind) approach because histologic results for collected biopsy specimens (inflammatory, necrotic, or hemorrhagic disease) suggested the specimens were nonrepresentative of the underlying disease process identified via CT (aggressive or malignant disease).

CLINICAL FINDINGS

Clinical signs at the time dogs were evaluated included open-mouth breathing, sneezing, or unilateral epistaxis. Histologic findings pertaining to the original biopsy specimens were suggestive of benign processes such as inflammation. In an attempt to obtain better representative specimens, a frameless CT-guided stereotactic biopsy system (CTSBS) was used to collect additional biopsy specimens from masses within the nasal and sinus passages of the dogs. The second set of biopsy specimens was histologically evaluated.

TREATMENT AND OUTCOME

Histologic evaluation of biopsy specimens collected via the CTSBS revealed results suggestive of malignant neoplasia (specifically, chondrosarcoma, hemangiopericytoma, or undifferentiated sarcoma) for 3 dogs, mild mixed-cell inflammation for 1 dog, and hamartoma for 1 dog. No complications were reported. These findings resulted in a change in treatment recommendations for 3 dogs and confirmed that no additional treatment was required for 1 dog (with hamartoma). For the remaining dog, in which CT findings and clinical history were strongly suggestive of neoplasia, the final diagnosis was rhinitis.

CLINICAL RELEVANCE

Biopsy specimens were safely collected from masses within the nasal and sinus passages of dogs by use of a frameless CTSBS, allowing a definitive diagnosis that was unachievable with other biopsy approaches.

Bilateral hamartomatous medullary lipoma within the nasal turbinate bones in a cynomolgus monkey (Macaca fascicularis)

A 15-year-old male cynomolgus monkey (Macaca fascicularis) showed large bilateral masses in the maxillary sinus. In histopathological examination, both masses revealed benign medullary lipomas within the turbinate bones. The tumors were composed of well-developed lipocytes, trabecular bones and a few blood vessels. Although we initially diagnosed the tumor as bilateral lipomas in the nasal turbinates, it was not differentiated from lipomatous hamartoma. Findings, such as unique symmetrical proliferation, lack of border from the normal marrow and the intact surrounding tissue, indicated a lipomatous hamartoma/hamartomatous lipoma, thought to be a suitable diagnosis of the lesion. Of most interest was that such a proliferating lesion occurred in the nasal turbinate.

Congenital Cystic Polypoid Rectal Hamartoma in a Newborn Foal

A neonatal foal with signs of rectal bleeding was diagnosed with an intraluminal rectal mass and intussusception on surgical exploration of the abdomen. Histologically, the mass consisted of cystic spaces lined by simple columnar epithelium with numerous goblet cells and was surrounded by thin bands of smooth muscle in a myxomatous stroma. Although the mass shared similarities with retrorectal cystic hamartoma (tailgut cyst) and juvenile polyps, described in human medicine, location and histologic findings were not entirely consistent with either condition.

Mesenchymal Hamartoma of the Liver in a Late-Term Equine Fetus

Mesenchymal hamartoma of the liver is a rare congenital disorder of biliary tract development. During the necropsy of a late-term equine fetus, a markedly enlarged liver of more than two times normal weight was found. Light microscopic review revealed that the normal hepatic parenchyma had been obliterated, replaced, and expanded by abnormal bile ducts surrounded by abundant, myxoid stroma. The lesion was diagnosed as a mesenchymal hamartoma. Small portions of the liver had bridging septa of fibrosis and proliferations of small-caliber abnormal bile ducts, resembling another congenital biliary abnormality termed congenital hepatic fibrosis.

Cranial Nerve Hamartoma in a Dog

An 11-year-old, male, neutered Cavalier King Charles spaniel was euthanatized because of recurrent seizures and inflammatory bowel disease. An incidental finding at necropsy was the presence of bilateral, firm, white nodules across the petrosal crest of the skull. Microscopically, the nodules were composed of normal myelinated nerve fibers within a mucinous stroma. A diagnosis of cranial nerve hamartoma was made.

Solitary Biliary Hamartoma with Cholelithiasis in a Domestic Rabbit (Oryctolagus cuniculus)

Hamartomas of the liver and biliary system are extremely rare entities in both animals and humans. Biliary hamartomas in humans are usually multiple and constitute the von Meyenburg complexes. This report describes the presence of a large solitary mass arising from the edge of the right medial liver lobe of a domestic rabbit. Histologically, the mass was composed of an extensive network of large varying sized cystic structures lined by simple cuboidal to columnar epithelium within an abundant fibrous stroma. Within many of the cyst lumina were varying sized, pale white to greenish hard concretions identified as choleliths and were analyzed and found to be composed of calcium carbonate. This is the first known report of biliary hamartoma with cholelithiasis in rabbits.

Bilateral Maxillary Periodontal Ligament Hamartoma in a Dog

A 12.5-year-old dog was presented for severe periodontal disease and bilateral maxillary enlargement. Radiographs of the maxilla showed generalized root resorption, ankylosis, and rarefaction of bone with focal radiodense areas. Surgical tooth extraction of multiple maxillary teeth and bilateral incisional biopsies of the periodontal tissue and maxilla in the legion of the maxillary fourth premolars were performed. Histopathologic examination showed features typical of fully differentiated periodontal ligament with abundant cementum/alveolar lining bone and sparce odontogenic epithelial cell rests. Histopathology in conjunction with radiographic and clinical signs suggested a diagnosis of bilateral periodontal ligament hamartoma. Examination 3-months postoperatively indicated uncomplicated healing of the extraction and biopsy sites with no resolution of the maxillary enlargement.

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.

Lip salivary-gland hamartoma in a cynomolgus macaque (Macaca fascicularis)

An incidental, asymptomatic, well-circumscribed, solitary, submucosal nodular mass was detected on the mucosal surface of the inner lower lip in a female cynomolgus macaque (age, approximately 2.4 y) during a juvenile chronic toxicology study. Grossly, the nodule was soft with brown to tan discoloration and measured approximately 4 mm in diameter. Microscopically, the nodule was covered by normal stratified squamous epithelium and composed of well-circumscribed irregular lobules containing hyperplastic and normal-appearing mucinous salivary gland acini and ducts, which were separated by thick connective tissue septae. In light of the gross pathology and results of microscopic examination, salivary gland hamartoma was diagnosed. This lesion resembles adenomatoid hyperplasia of mucous salivary glands in humans, which is a rare nonneoplastic swelling. To our knowledge, this case description is the first report of a cynomolgus macaque with the rare entity of lip salivary gland hamartoma, which likely represents adenomatous hyperplasia in humans.

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.

Benign placental mass with fetal growth retardation in a bull mastiff

A 4-year-old bull mastiff presented due to premature labour. The referring veterinarian elected to perform a caesarian delivery and at the time of surgery a 4×4×2 cm round, smooth, red to tan, lobulated soft mass was identified attached to the allantoic surface of the zonary placenta of one pup. Microscopically, this mass was composed of loosely arranged confluent undulating cords of polygonal to columnar epithelioid cells separated by a fine fibrovascular stroma resembling the placental labyrinth. The labyrinthine structure and epithelioid nature of the cells suggested that the mass was of trophoblastic origin. Due to the non-invasive nature of the mass and relatively low mitotic activity, this proliferative trophoblastic mass was considered to be benign. The absence of morphological features supporting malignant behaviour and the recapitulation of the normal labyrinthine architecture led to the diagnosis of a trophoblastic hamartoma. To the authors' knowledge this is the first report of a placental hamartoma in the dog.

A vascular hamartoma arising from the cervical spine of a cat

A 15-month-old cat presented for evaluation of worsening generalized proprioceptive ataxia. Computed tomography of the cervical spine revealed the presence of a compressive extradural bony mass involving the dorsal aspect of C1. Surgical exploration and debulking of the mass was performed. Histological evaluation of the mass revealed fibrovascular tissue consistent with a vascular hamartoma. This mass was deemed to be originating from the soft tissue associated with the C1 vertebra with subsequent bony proliferation. Surgical debulking of the mass resulted in complete resolution of clinical signs with no evidence of recurrence 2 years after surgery.

Fibrous vaginal hamartoma in a newborn calf

A 2-day-old female Holstein calf was presented for abnormal structures protruding from the vulva at birth. A diagnosis of fibrous vaginal hamartoma was made, based on macroscopic and histologic examinations of the abnormal tissue. Management of this case involved surgical mass ablation.

Cutaneous neoplasms in pet rabbits: a retrospective study

Over a 16-year period, 190 tumors and tumorlike lesions from 179 pet rabbits were submitted for histopathologic examination. A total of 23 different tumor types and 1 tumorlike lesion were diagnosed. The most common diagnoses were trichoblastoma, collagenous hamartoma, and Shope fibroma. Viral-induced tumors were Shope fibroma (19) and Shope papilloma (2). Common nonviral epithelial tumors included trichoblastoma (59), squamous cell carcinoma (5), squamous papilloma (4), trichoepithelioma (3), and apocrine carcinoma (3). Common mesenchymal tumors were lipoma (10), liposarcoma (3), myxosarcoma (9), malignant peripheral nerve sheath tumor (8), fibrosarcoma (7), and leiomyosarcoma (4). Malignant melanoma was diagnosed in 8 rabbits. Collagenous hamartomas were diagnosed in 26 rabbits. Mesenchymal proliferations occurred significantly more often in male rabbits than in females. Collagenous hamartomas and myxosarcomas occurred exclusively in male animals, and 3 rabbits had multiple collagenous hamartomas. Immunohistochemistry was applied in cases in which a definite diagnosis could not be reached on hematoxylin and eosin slides. Follow-up information was received in 19 cases. Carcinomas recurred (2 of 3) or metastasized (1 of 3), whereas sarcomas frequently recurred (7 of 12). One malignant melanoma (1 of 3) and one poorly differentiated round cell neoplasm recurred (1 of 1). This is the first comprehensive retrospective analysis on skin neoplasia in pet rabbits.

Fibroepithelial hamartoma in a domestic pig

This case report is the first description of a fibroepithelial hamartoma in a pig. The dysplasia, which covered half of the face of the newborn piglet, did not increase in relative size until the animal was euthanatized at 6 months of age. Histologic examination revealed a moderate orthokeratotic hyperkeratosis with variable degrees of epithelial proliferation. The main body of the dysplasia consisted of collagenous fibers. In addition, some proliferating small blood vessels as well as focally gathered dilated apocrine glands were evident. Given morphologic and clinical features, the diagnosis of a hamartoma seemed to be justified.

Cardiac Vascular Hamartoma in Two Slaughtered Cattle

Two cases of cardiac vascular hamartoma were detected in slaughtered cattle. In each case, a single nodular protrusion (ca 2.5 cm in diameter) was located in the same part of the right atrium. Tortuous vessels of variable size with irregular lumina were seen on the cut surface of each nodule. Microscopically, there were many dysplastic vascular structures within the nodules. The vascular structures showed various changes such as irregular thickening of the tunica intima and the tunica media, walls with variable amounts of fibres (elastic, collagen and smooth muscle), some of which were disarranged. Mature adipose tissue and fibrous connective tissue were seen close to the vascular structures and intervascular tissue. In the nodules, bundles of cardiac muscle were disorganized, intermingled with connective tissue, and in some areas embedded within fibrous connective tissue.

Vascular Hamartoma as the Cause of Hind Limb Lameness in a Horse

We report a 5-year-old gelding with a rare benign tumour of 2-month duration in the subcutis of the hind limb that presented with lameness. Physical examination revealed normal vital signs. Laboratory findings were within normal ranges. No bone abnormalities were detected on radiographic examination of the affected area. Bloody fluid was obtained by aspiration. Through an I-shape skin incision the tumour was excised en-block. Microscopic study showed a vascular hamartoma characterized by cavernous haemangiomatous tissue and proliferation of multiple vessels of variable diameter. This report highlights the importance of limb vascular hamartoma, as an infrequent lesion, in the differential diagnosis of lameness in the horse.

Ovarian vascular hamartoma in a cow

A 5-year-old Holstein cow was examined for a unilateral enlarged ovary. A clinical diagnosis of ovarian tumor was established before a histological diagnosis of ovarian vascular hamartoma was made. Ovarian vascular hamartoma has not been reported previously in a live animal.

Multiple papillomavirus-associated epidermal hamartomas and squamous cell carcinomas in situ in a dog following chronic treatment with prednisone and cyclosporine

A 4-year-old, spayed female toy fox terrier developed multiple epidermal hamartomas and squamous cell carcinomas in situ following chronic immunosuppressive therapy with prednisone and cyclosporine for management of an immune-mediated nonregenerative anaemia. Immunohistochemical staining was positive for papillomavirus antigen within both benign (n = 19) and malignant (n = 8) cutaneous lesions that developed during a 3-year period of observation, with positive staining most often seen in keratinocytes in the granular cell layer. Treatment of the papillomavirus infection with interferon-alpha was discontinued after 2 weeks because of diarrhoea and a further increase in liver enzymes. The cutaneous lesions of this dog persisted and new lesions developed during the year following discontinuation of both cyclosporine and prednisone. This is the first reported case of papillomavirus-associated squamous cell carcinoma in situ developing in a dog following chronic administration of cyclosporine and prednisone.

Simultaneous expression of COX-2 and mPGES-1 in mouse gastrointestinal hamartomas

Cyclo-oxygenase (COX)-2 is induced in various types of cancer tissues. Here, we demonstrate stromal expression of both COX-2 and microsomal prostaglandin E₂ synthase (mPGES)-1 in gastrointestinal hamartomas developed in Lkb1^+/−, Smad4^+/− and Cdx2^+/−mice. These results suggest that PGE₂ produced by COX-2 and mPGES-1 plays an important role in hamartoma development regardless of the mutated genes causing hamartomas.

Cutaneous smooth muscle tumors in the dog and cat

Cutaneous smooth muscle tumors may arise from arrector pili muscles and from smooth muscles of the dermal vasculature. This report describes histologic and immunohistochemical features of eight arrector pili hamartomas in 8 dogs, 15 piloleiomyomas in 10 dogs and 3 cats, 10 piloleiomyosarcomas in 9 dogs and 1 cat, 1 angioleiomyoma in 1 cat, and 9 angioleiomyosarcomas in 6 dogs and 3 cats. Hamartomas and tumors arising from arrector pili muscles preferentially originated from the dorsal trunk. 5/5 (100%) arrector pili hamartomas, 10/12 (83%) piloleiomyomas, 4/5 (80%) piloleiomyosarcomas, 1/1 (100%) angioleiomyoma, and 6/7 (86%) angioleiomyosarcomas were positive for smooth muscle actin. 5/5 (100%) arrector pili hamartomas, 10/12 (83%) piloleiomyomas, 4/5 (80%) piloleiomyosarcomas, 1/1 (100%) angioleiomyoma, and 1/7 (14%) angioleiomyosarcomas were positive for desmin. Two incompletely excised canine angioleiomyosarcomas recurred locally. Metastases were not reported.

Smooth Muscle Hamartoma of the Abomasum in a Calf

This report describes a case of smooth muscle hamartoma of the abomasum in a 6-month-old steer humanely killed because of severe pneumonia. At necropsy, marked thickening of the abomasal wall in the area of the pylorus was found. On cut section, the thickness of the submucosal layer, extending from the submucosa to the muscularis propria, was seen to be increased to 3 cm. The upper (i.e., nearest to the gut lumen) half of the sectioned thickening was composed mainly of adipose-like tissue and the lower half mainly of muscle-like tissue. Histologically, the submucosal layer was composed of fibroadipose tissue, within which were embedded, to varying degrees, numerous well-defined, haphazardly oriented, thin to thick bundles of smooth muscle fibres. This appears to be the first report of smooth muscle hamartoma of the stomach or abomasum in animals, including man.

Abdominal fluid from a dog

A 2-year-old intact female mixed-breed dog with a 1-month history of lethargy and anorexia was evaluated for abdominal distension and an abdominal mass. The dog's last heat cycle, her third, was 1 month prior to presentation, and no reproductive cycle abnormalities were noted at any time. Hematologic and serum biochemical abnormalities were consistent with hemorrhage and inflammation. Ultrasonographic examination confirmed a large midabdominal mass and a moderate amount of abdominal fluid. Cytologically, the fluid showed evidence of pyogranulomatous inflammation, hemorrhage, and mesothelial reactivity, as well as ciliated columnar cells and free cilia that were interpreted as likely of oviductal origin. The mass was removed surgically, and the histopathologic interpretation was oviductal hamartoma with marked stroma formation and acute hemorrhage. To the authors' knowledge, this is the first reported case of oviductal hamartoma in any species and the first reported case detailing the finding of ciliated columnar epithelial cells in the abdominal fluid of a dog. Ciliated columnar epithelial cells in abdominal fluid should be considered indicative of a likely underlying oviductal lesion.

Congenital tumours and tumour-like lesions in domestic animals. 3. Horses. A review

The literature on congenital tumours and tumour-like lesions in horses was reviewed. Included were embryonic tumours and teratomas. Special attention was paid to the ubiquitous adenomatous hyperplasia of the placenta. It appears that temporal teratomas, interstitial hamartomas and placental adenomatous hyperplasia are unique in the horse. Benign teratoma of the undescended testis is far more frequent in the horse than in other species. In horses, as in calves and pigs, congenital skin tumours were of papillomatous, vascular and melanocytic types. The sporadic occurrence of congenital tumours in the horse did not provide an etiologic or pathogenetic clue. The possibility of oncogenic viruses in cases of congenital skin papilloma or malignant lymphoma could neither be proven, nor be excluded. Hereditary tumours were not encountered.

Congenital and hereditary tumours in domestic animals. 2. pigs. A review

The literature on congenital and hereditary tumours in pigs was reviewed. One hitherto unreported own case was added. Sporadic cases of congenital tumours included several types found in newborn piglets. Embryonic tumours (nephroblastoma, rhabdomyosarcoma) occurred either in newborn or in juvenile animals. Cardiac rhabdomyomas were provisionally classified as hamartomas. The hereditary tumours, melanomas and lymphomas, were reproducible by experimental matings. These tumours are particularly interesting as models to elucidate genetic and immunologic mechanisms of tumour diseases. Striking is the high degree of regression in porcine melanomas and the associated melanosis.

Myocardial hamartoma of the right atrium in a dog

A myocardial hamartoma of the right atrium is described in an 8-year-old dog that died from pneumonia. At necropsy, a firm, mottled, dark-brown right atrial appendage, of normal shape but slightly enlarged, was found incidentally. On section, the right atrial appendage was composed of a grey-tan, solid mass. Histological features of the mass were as follows: the component cells were mature cardiac muscle cells; the mass contained all of the components of the normal heart wall (i.e., epicardium, myocardium and endocardium), but the arrangement of the component tissues was disorganized; growth of the mass was non-invasive, and continuity of the component cells with adjacent normal myocardial cells was evident, suggesting a congenital origin. This appears to be the first report of congenital myocardial hamartoma in any animal other than man.

Surgical treatment of an intramedullary spinal cord hamartoma in a dog

A 9-year-old spayed female Golden Retriever was examined because of progressive hind limb lameness. Magnetic resonance imaging of the thoracic and lumbar portions of the vertebral column revealed a focal, contrast-enhancing, intramedullary spinal cord mass. The history, signalment, and magnetic resonance findings were suggestive of spinal cord neoplasia. A hemilaminectomy, durotomy, and longitudinal myelotomy were performed, and a 1 X 1-cm mass that contained numerous blood vessels was removed with blunt dissection. Results of histologic examination and immunohistochemical staining of the mass suggested that it was a hamartoma. The dog improved after surgery, with no evidence of a recurrence of clinical signs 14 months after surgery. Vascular malformations of the CNS in dogs include hamartomas, hemangiomas, angiomas, hemangioblastomas, meningocerebral hemangiomatosis, and arteriovenous malformations. A hamartoma is a non-neoplastic overgrowth of cells or an improper proportion of cells that are normally in the involved tissue. Although magnetic resonance imaging may be helpful in determining the extent of the lesion in dogs with vascular malforrmations, it cannot be used to distinguish neoplastic from non-neoplastic formations. Excision may result in a good outcome for dogs with an intramedullary spinal cord hamartoma.

Cutaneous vasoproliferative lesions in goats

Abstract. In a retrospective survey of caprine neoplastic disease, eight masses were diagnosed as cutaneous vascular tumors. The typical clinical presentation was a solitary raised, bleeding mass. No predilection with regard to age, breed, sex, or anatomic location was found. Reevaluation of the microscopic features of the masses resulted in diagnoses of hamartoma (2), hemangioma (4), and hemangiosarcoma (2). An endothelial cell origin was confirmed in all seven tumors tested immunohistochemically for factor VIII-related antigen. Although rarely reported, goats display a range of cutaneous vascular growth abnormalities similar to those observed in other domestic animals.

An ovarian interstitial cell hamartoma in a newborn foal

A case of congenital ovarian interstitial cell hamartoma in a thoroughbred foal that died of apparent nutritional myopathy (white-muscle disease) 14 h after birth is described. An incidental finding at necropsy was a pale brown, mushroom-shaped, pedunculated mass (6 x 4 x 3 cm) attached to the left ovary. On the cut surface, the mass had a peripheral rim of dense parenchyma (3-5 mm wide), surrounding a pale gelatinous core. Histologically, the mass consisted of a peripheral zone of densely packed large cells that were quite similar, morphologically, to fetal ovarian interstitial cells, and a central area of small nests of similar cells scattered within an extremely loose connective tissue matrix. Immunohistochemically, intracytoplasmic positive labelling for inhibin was detected in these cells. These observations suggest that the lesion was an ovarian interstitial cell hamartoma.

Spontaneous pulmonary neoplasms in cynomolgus monkeys (Macaca fascicularis)--a report of two cases

The first lung tumour-bearing animal was a 7 years and 3 months old cynomolgus monkey. Microscopic examination revealed a neoplastic mass under the pleura that consisted of squamous islands with little keratinization, multifocal mineralization of the keratin, inflammatory cell and foreign body-type giant cell infiltration. It was classified as pulmonary squamous cell carcinoma. In a second cynomolgus monkey (2 years and 10 months old) a lung mass was observed at necropsy. Microscopically the tumour consisted of numerous islands of cartilage with glandular structures lined by a cuboidal epithelium between them. The neoplasm was classified as cartilaginous hamartoma.

Vascular hamartoma within the flexor muscles of the left carpus in a dog

A three-year-old male bearded collie was presented with a history of left thoracic limb lameness and a fluctuant non-painful swelling within the flexor tendons of the left carpus. Investigations included ultrasonography, laboratory analysis of fluid aspirated from the lesion and positive contrast radiography. Treatment involved surgical resection of the lesion from the local flexor muscles of the carpus. Histologically, the resected tissue was considered to represent a vascular hamartoma associated with the pronator quadratus muscle.

Cerebral vascular hamartomas in five dogs

Vascular hamartomas are considered developmental lesions rather than true neoplasms. Reports of such anomalies in the canine brain are scarce, and their classification is confusing. This case series of vascular hamartomas from the brains of five dogs was characterized using histochemistry and immunohistochemistry, in addition to gross and microscopic findings. All five hamartomas were located in the telencephalon, three in the pyriform lobe, without any predilection for the left or right side. Each hamartoma consisted of a proliferation of thin-walled vessels which varied in caliber. These vessels were elastin-negative, with varying amounts of collagen and no muscular component. In four of the five hamartomas, lining cells were actin- and factor VIII-positive. All five hamartomas contained glial fibrillary acid protein (GFAP)-positive parenchyma at moderate to high frequency, and four contained neurofilament-positive axons between component vessels. This report shows that vascular hamartomas in the canine brain are structural malformations for which immunohistochemistry is useful for accurate classification.

Pulmonary microcystic hamartoma in an adult dog

Microcystic hamartoma was detected as a tumorlike mass in the left caudal lung lobe of a 12-year-old mixed-breed dog. Histologically, the mass was characterized by microcysts of various sizes that mimicked alveoli and were surrounded by thin fibrous septal tissue. However, unlike the adjacent lung parenchyma, bronchial or bronchiolar trees were absent, and the septal vascular channels were extremely underdeveloped. Immunohistochemically, the cells lining the microcysts were consistently positive for cytokeratin but not for vimentin, whereas the septal fibroblast-like cells were negative for cytokeratin and positive for vimentin. Electron microscopy confirmed that the microcysts were lined with a layer of type I and type II mature pneumocytes. This is the first description of the detailed morphologic features of microcystic hamartoma.

Subependymal astrocytic hamartomas in the Eker rat model of tuberous sclerosis

Tuberous sclerosis (TSC) is an autosomal dominant syndrome that is linked to two genetic loci: TSC1 (9q34) and TSC2 (16p13). Brain manifestations such as cortical tubers and subependymal hamartoma/giant cell astrocytomas are major causes of TSC-related morbidity. In this study, we describe the central nervous system involvement in a unique rodent model of tuberous sclerosis. The Eker rat carries a spontaneous germline mutation of the TSC2 gene and is predisposed to multiple neoplasia. In a series of 45 adult Eker carriers (TSC2 +/-), three types of focal intracranial lesions were found, of which the subependymal and subcortical hamartomas were most prevalent (65%). There exist remarkable phenotypic similarities between the Eker rat and human subependymal lesions. Our study indicates that the predominant cellular phenotype of the subependymal hamartomas is astroglial and suggests that the neuronal contribution within these lesions is, in part, the result of pre-existing myelinated axons. The hamartomas did not show evidence of loss of the wild-type TSC2 allele; it remains to be determined whether TSC2 inactivation is necessary for their pathogenesis. This genetically-defined rodent model may be useful in elucidating the molecular and developmental basis of the subependymal giant cell astrocytoma in humans.

Congenital polyalveolar lobe in three foals

Three cases of congenital polyalveolar lobe (pulmonary hamartoma) were diagnosed in female Thoroughbred foals. Foal 1 was born at full term but died shortly afterwards. Foal 2 was aborted at the seventh month of gestation. Parturition was induced at the tenth month of gestation in foal 3 because it developed hydrops of the amnion and ascites. In all three foals, the polyalveolar lobe occurred on the right side and affected the entire right lung. In each case, the right lung formed a tumour-like mass, and expanded into the left chest cavity. The lung masses were pink to dark red and spongy to rubbery, with marked lobular patterns on the pleural and cut surfaces. The left lung was compressed and small. The right and left lungs weighed 0.9-6.3 kg and 80 g-0.3 kg, respectively. Microscopically, the polyalveolar lobe consisted of normal alveoli, bronchioli and blood vessels, but the alveolus:artery ratio was greater than normal. In the polyalveolar lobe of two foals the numbers of alveoli per artery were 65.2 and 52.5; in contrast, the corresponding values for three control lungs were 26.9, 26.5 and 27.6. Chronic passive congestion with generalized oedema was observed in foals 2 and 3.

Splenic hamartoblastoma in a sow

Multiple lesions of splenic hamartoblastoma were found incidentally in a 2- to 3-year-old crossbred sow. The predominant cells, characterized by extreme nuclear irregularity and hemidesmosome-like structures, were considered to be derived from reticular cells of the spleen, and demonstrated infiltrative growth. Their cytological atypism and growth pattern suggest that the present lesions are true neoplasms.

Hamartomatous polyps in the intestine of two dogs

Partly obstructing, proliferative mucosal masses in the small intestine of two dogs were shown histologically to be hamartomatous polyps. They were characterized by an extension of smooth muscle from the muscularis mucosae into the lamina propria of the lesion. This is the first report of such lesions in domestic animals. In one of the dogs the lesion had become malignant.