Rhabdomyosarcoma of the tongue in a dog

Rhabdomyosarcoma of the tongue in a neonatal calf

A newborn male Holstein calf developed a nodular enlargement at the tip of the tongue. Histopathological examination of the mass revealed predominant proliferating small, round, spindloid or polygonal neoplastic cells with scattered myoblast- and myotube-like cells and multinuclear giant cells. Phosphotungstic acid haematoxylin staining revealed cytoplasmic cross-striations in a few neoplastic cells. Neoplastic cells were immunopositive for vimentin, desmin, myoD1, myogenin, myoglobin and α-smooth muscle actin. The mass was diagnosed as embryonal rhabdomyosarcoma. To the best of our knowledge, this is the first reported case of bovine congenital lingual rhabdomyosarcoma, which is rare in animals.

Clinical, pathological and therapeutic findings on lingual rhabdomyosarcoma in a dog - case report

ABSTRACT The biological behaviour of the tumours vary according to the species in which they occur, its location within the cavity, clinical stage and histopathological nature. Lingual neoplasms are generally uncommon in companion animals. Rhabdomyosarcomas are malignant, solid, aggressive formations with high metastatic potential. The clinical signs are variable and a definitive diagnosis can only be reached through histopathological analysis of biopsy and necropsy specimen. In some cases, immunohistochemical study may be needed to confirm the diagnosis. This paper aims to highlight important points about this uncommon condition in dogs, using a case report of lingual rhabdomyosarcoma, which showed no evidence of metastasis after diagnosis, nor of local recurrence after surgical excision with a wide safety margin. It was concluded that early diagnosis, the correct interpretation of the complementary tests and the appropriate therapeutic approach contributed to improving the quality of life and survival of the patient in question.

Diagnosis and Multimodal Treatment of Metastatic Maxillofacial Juvenile Embryonal Rhabdomyosarcoma in a Young Golden Retriever

A 2 yr old male castrated golden retriever was evaluated for a rapidly progressing maxillofacial spindle cell tumor. On examination, an ill-defined left maxillary mass, a 2 cm swelling under the left eye, and an enlarged left mandibular lymph node were noted. The dog was bright and alert but appeared painful upon jaw extension. Cytology from the lymph node revealed metastatic disease. Thoracic radiographs and computed tomography scan revealed pulmonary nodules. Computed tomography of the head and neck revealed a 6.7 × 4.1 × 6.5 cm mass at the rostral aspect of the left zygomatic arch invading the orbit. A second opinion of the biopsy specimen in conjunction with positive immunohistochemical staining for desmin led to a revised diagnosis of rhabdomyosarcoma. Treatment consisted of three doses of palliative radiation therapy, in 8 Gy fractions, and chemotherapy with vincristine, cyclophosphamide, and doxorubicin. A rapid clinical response was noted shortly after treatment initiation; however, the response was temporary, and the dog was euthanized due to widespread metastatic disease and associated clinical signs 74 days after initial therapy. This is one of the first reports describing positive results from multimodal treatment with chemotherapy and radiation therapy of a maxillofacial juvenile rhabdomyosarcoma in the veterinary literature.

A Comparative Review of Canine and Human Rhabdomyosarcoma With Emphasis on Classification and Pathogenesis

Rhabdomyosarcomas are a diverse group of malignant mesenchymal neoplasms exhibiting variable levels of differentiation toward skeletal myocytes. Neoplastic cells may resemble relatively undifferentiated myoblasts, satellite cells, or more differentiated elongated spindle cells and multicellular myotubes. In veterinary medicine, classification into subtypes and variants is based on an outdated system derived from human pathology and is solely based on histologic characteristics. In contrast, classification of human rhabdomyosarcoma is based on histologic, immunohistochemical, and molecular diagnostic techniques, and subclassification has clinical and prognostic relevance. Relevance of tumor subtyping has not been established in veterinary medicine. Recent discoveries of components of the molecular pathogenesis and genomes of human rhabdomyosarcomas have led to new diagnostic techniques and revisions of the human classification system. The current classification system in veterinary medicine is reviewed in light of these changes. Diagnosis of rhabdomyosarcoma using histopathology, electron microscopy, and the clinical aspects of human and canine rhabdomyosarcomas is compared. The clinical features and biologic behavior of canine rhabdomyosarcomas are compared with canine soft tissue sarcomas.

Sublingual reactive histiocytosis in a dog

Lingual lesions are relatively uncommon in dogs and are mostly represented by neoplasms and glossitis secondary to trauma or infections. Reactive histiocytosis is an uncommon, poorly understood, reactive disorder characterized by proliferation of activated, interstitial, dendritic, antigen-presenting cells associated with lymphocytes and neutrophils with a specific angiocentric orientation and occasional angioinvasion and angiodestruction. Clinically, the disease has a waxing and waning behavior with possible response to treatment and regression, or progression to multiple lesions and internal organ involvement. This case report describes an unusual sublingual presentation of reactive histiocytosis in a Miniature Pinscher dog. The diagnosis was obtained by clinical and histopathological exclusion of other causes, detection of the characteristic microscopic growth pattern, and by immunocytochemistry. Histiocytic cells were vimentin, CD18, CD11c, and CD1c positive consistent with a dendritic cell origin. Anti-BCG stain (Bacillus Calmette and Guerin) was negative for etiological agents. The dog was treated with oral administration of tetracycline and niacinamide during an 8-month period. There was no indication of recurrence of the sublingual mass 2-years following treatment.

Embryonal Rhabdomyosarcoma in a Young Maine Coon Cat

Embryonal rhabdomyosarcomas are uncommon tumors in all domestic species, especially cats. A 14-month-old Maine coon was diagnosed with an embryonal rhabdomyosarcoma in the rectus abdominus muscle, which was treated with complete surgical excision. Although no clinical progression was noted after surgery, the cat succumbed to pulmonary metastasis within 7 months. The histological diagnosis was embryonal rhabdomyosarcoma (myotubular subtype). This category of striated muscle tumors is thought to have a more aggressive clinical course. The rapid demise of this cat even with no clinical or histological evidence of metastasis at the time of resection may indicate that, as in human medicine, adjuvant chemotherapy should be considered in conjunction with early surgical excision in preventing disease progression.

What is your diagnosis? Lingual mass in a dog

A 3.5-year-old female spayed Rat Terrier was presented for evaluation of a submucosal lingual mass. Fine-needle aspiration of the mass revealed a population of neoplastic cells composed predominantly of small, round cells and large, round to spindle-shaped cells, which occasionally had blunt cytoplasmic borders and multiple nuclei. The neoplastic cells had moderate to marked anisocytosis and anisokaryosis. The cytologic interpretation was malignant neoplasia, most likely sarcoma. Histopathologic examination of a biopsy specimen revealed an unencapsulated, poorly demarcated, moderately cellular neoplasm composed of individualized, infiltrative spindle cells. Elongate skeletal muscle cells with prominent, rectangular borders (strap cells) were observed. A morphologic diagnosis of rhabdomyosarcoma was made. Staining with phosphotungstic acid-hematoxylin revealed haphazardly arranged skeletal muscle cross-striations. Immunohistochemical staining results for vimentin, Myo D1, desmin, and myoglobin were positive, though staining intensity of tumor cells varied with the degree of differentiation. Using transmission electron microscopy, irregular, disorganized Z-bands were identified. Rhabdomyosarcomas are uncommon tumors in the dog, and rarely may involve the tongue or oral cavity. Cytologic evaluation of a rhabdomyosarcoma may reveal a pleomorphic population of cells and definitive diagnosis may require histologic examination, immunohistochemical staining, and electron microscopy.

Maxillofacial rhabdomyosarcoma in the canine maxillofacial area

Three dogs had a diagnosis of maxillofacial rhabdomyosarcoma. These dogs were treated with surgery and/or radiotherapy, and had poor clinical responses. The tumor tissues in all three cases were observed around the upper premolar teeth with ulcerative lesions and CT examinations in each case revealed extensive bony involvement into the maxilla. Two cases were subjected to surgical excision of the tissues, followed by an external radiation therapy. The other case was only treated with palliative radiation. Outcomes of the treatment of all the cases were quite poor because of the invasive and refractory nature of the tumor cells, leading to the local recurrence and lung metastasis early in the clinical course. All dogs died within two months of the first admission.

Lingual haemangiosarcoma in a crossbred dog

An eight-year-old, male neutered, crossbred dog was presented for investigation of a lingual mass of four months duration. Oral examination revealed a 7 cm × 5 cm soft, fluctuant mass at the caudal aspect of the tongue. Ultrasound examination of the mass demonstrated mixed echogenicity, with cavitations containing hypoechoic and anechoic regions. Lingual haemangiosarcoma was diagnosed on histopathological examination of multiple biopsy samples, with confirmation of the vascular endothelial origin of tumour cells by positive immunolabelling for factor VIII-related antigen.

Frequency of and risk factors associated with lingual lesions in dogs: 1,196 cases (1995-2004)

OBJECTIVE

To categorize histologic lesions affecting the tongue, determine the frequency with which they develop, and identify risk factors associated with their development in dogs.

DESIGN

Retrospective case series.

ANIMALS

1,196 dogs.

PROCEDURES

Diagnostic reports of lingual biopsy specimens from dogs evaluated from January 1995 to October 2004 were reviewed.

RESULTS

Neoplasia comprised 54% of lingual lesions. Malignant tumors accounted for 64% of lingual neoplasms and included melanoma, squamous cell carcinoma, hemangiosarcoma, and fibrosarcoma. Large-breed dogs, especially Chow Chows and Chinese Shar-Peis, were at increased risk for melanoma. Females of all breeds and Poodles, Labrador Retrievers, and Samoyeds were more likely to have squamous cell carcinomas. Hemangiosarcomas and fibrosarcomas were commonly diagnosed in Border Collies and Golden Retrievers, respectively. Benign neoplasms included squamous papilloma, plasma cell tumor, and granular cell tumor. Small-breed dogs, especially Cocker Spaniels, were at increased risk for plasma cell tumors. Glossitis accounted for 33% of diagnoses; in most cases, the inciting cause was not apparent. Whereas large-breed dogs were more likely to have lingual neoplasia, small-breed dogs were more likely to have glossitis. Calcinosis circumscripta accounted for 4% of lingual lesions and predominately affected young large-breed dogs. The remaining submissions consisted mostly of various degenerative or wound-associated lesions.

CONCLUSIONS AND CLINICAL RELEVANCE

The frequency of lingual lesions was not evenly distributed across breeds, sexes, or size classes of dogs. Veterinarians should be aware of the commonly reported lingual lesions in dogs so that prompt diagnosis and appropriate management can be initiated.

Multifocal rhabdomyosarcomas within the tongue and oral cavity of a dog

A 10-year-old terrier crossbreed presented with a change in bark intonation of 3-4 month's duration and pronounced panting. Four variably sized masses were observed within the oral cavity. The largest mass was located within the parenchyma at the caudal region of the tongue. Others were located on the left arytenoid, within the soft palate, and in the oropharynx above the soft palate. Histopathologic specimens consisted of large round to polygonal cells occasionally containing multiple nuclei and rare faint cytoplasmic cross striations. Staining was weakly positive with periodic acid-Schiff. Immunocytochemistry was strongly diffusely positive for muscle-specific actin, myoglobin, and desmin and scattered positive for S-100 and vimentin. Phosphotungstic acid-hematoxylin staining enhanced cytoplasmic cross striations. The cytoplasm of all neoplastic cells was filled with mitochondria on electron microscopy. The final diagnosis was multifocal/metastatic rhabdomyosarcoma.

Major Glossectomy in Dogs: A Case Series and Proposed Classification System

Major resections of the tongue have not been commonly performed in animals because of concerns about the unfavorable postoperative effects of diminished lingual function. Five dogs were retrospectively reviewed to determine prehensile function and quality of life after glossectomies. Examinations were performed 1 week to 8 years after glossectomy, and owner interviews were conducted 10 months to 8 years after the surgery. All five dogs had acceptable and functional outcomes. Based on these five cases, glossectomy was well tolerated by dogs and may be a viable treatment option for aggressive tongue tumors and other conditions that render the tongue unsalvageable.

Perianal rhabdomyosarcoma in a dog

A perianal rhabdomyosarcoma was diagnosed in an 11-year-old neutered male Labrador retriever. Following two incomplete surgical excisions of the tumour, the dog was treated by means of surgery combined with local radiotherapy and systemic chemotherapy using one cycle of vincristine sulphate, doxorubicin and cyclophosphamide (VAC protocol). The dog died 252 days after the first combined therapy. Radiography at this time demonstrated enlargement of the iliac lymph nodes, suggesting metastasis of the tumour. To the authors' knowledge, this is the first report of treatment of canine perianal rhabdomyosarcoma.