Equine nasal and paranasal sinus tumours. Part 1: review of the literature and tumour classification.

The normal gross and histological anatomy of the equine nasal and paranasal sinuses are reviewed and the relationships between the local anatomy, the occurrence of different tumour types, and of tumour spread are examined. The histological classification of the more common equine sinonasal tumours and tumour-like lesions are discussed. Clinical and pathological descriptions of 50 more recently recorded such tumours are separately tabulated. The literature shows that equine sinonasal tumours, both endemic and sporadic, are relatively uncommon in horses, with non-neoplastic growths such as maxillary (sinus) cysts, progressive ethmoid haematoma and inflammatory nasal polyps more commonly recorded. The equine paranasal sinuses, especially the caudal maxillary sinus, are the most common sites for sinonasal tumours and, in contrast to other species, primary nasal tumours are uncommon. The more common tumour types include squamous cell carcinoma that, in some cases, arise in the oral cavity and spread to the maxillary sinuses; adenocarcinomas; bone and dental tumours; fibrosarcomas and haemangiosarcomas. Except for some benign bone tumours, there are few records of successful treatment of equine sinonasal tumours.

Equine nasal and paranasal sinus tumours: part 2: a contribution of 28 case reports.

The clinical and pathological findings of 28 cases (27 horses, 1 donkey) of equid sinonasal tumours examined at the Edinburgh Veterinary School are presented and include: seven cases of squamous cell carcinoma (SCC); five adenocarcinomas; three undifferentiated carcinomas; two adenomas; five fibro-osseous and bone tumours; and single cases of ameloblastoma, fibroma, fibrosarcoma, undifferentiated sarcoma, melanoma and lymphosarcoma. The median ages of animals affected with epithelial, and fibro-osseous/bone tumours were 14 and 4 years, respectively. Unilateral purulent or mucopurulent nasal discharge (81% of cases) and gross facial swellings (82% of cases) were the most common presenting signs with sinonasal tumours, with epistaxis recorded in just 23% of cases. Radiology and endoscopy were the most useful ancillary diagnostic techniques. The maxillary area was the most common site of tumour origin, and only three cases were definitively identified as originating in the nasal cavity. Four of the maxillary SCC lesions originated within the nasal cavities or maxillary sinuses, while two originated in the oral cavity. Fourteen of 15 carcinomas, but only two of the 13 remaining tumours, spread to other sites in the head. Only three cases of sinonasal tumour had lymph node metastases, and none had distant metastases. In the long term, surgical treatment with seven malignant tumours was unsuccessful (6 months median survival post-operatively), but was successful with four out of five benign tumours (no regrowth at a median of 4 years post-operatively).

Rumen papillomas in sheep.

Out of a sample of 200 rumens from sheep slaughtered in Edinburgh, papillomas were found in 25. They occurred as fibro-papillomas, mostly along the pillar of muscle between the dorsal and ventral rumen, and were often multiple. No inclusion bodies were seen in the lesions or papilloma virus particles on electron microscopy. Homogenisation of papillomatous tissue followed by various methods of purification did not yield identifiable virus particles, and viral DNA was not detected. Immunoperoxidase staining showed a very small number of positive cells at or on the surface of 6 out of 10 lesions examined. Thus, it seems probable that virus particles are not found in large numbers in the rumen papillomas of sheep, unlike the situation in ovine skin warts, but are present in a few epithelial cells which are rapidly shed from the surface of the mucous membrane.

Causes of death and sex differences in survival times of pigs with untreated hereditary lymphosarcoma (leukemia).

The survival times from birth of 39 entire male Large White pigs with hereditary lymphosarcoma (L/S) were significantly shorter than those of 76 affected females. The survival times of 19 male castrates were for the most part intermediate between those for entire males and females. Analysis of the cause of death revealed that pigs with L/S (L/S-P) were more likely than pigs without L/S to die from colibacillosis, but this disease showed to sex predisposition. In uncomplicated deaths from L/S, weights of splanchnic lymph nodes, spleen, and thymus were greatest in females. The cell-mediated and humoral antibody responses of L/S-P were significantly poorer against 2,4-dinitrofluorobenzene (DNFB) and sheep red blood cells, poorer against skin homografts, but better against bovine serum albumin than those of healthy littermates. Healthy females had stronger DNFB reactions than did healthy males or castrates. Castrated L/S-P responded to DNFB better than did females and significantly better than did entire males.

Growth in culture of adenocarcinoma cells from the small intestine of sheep.

Explant cultures were initiated from adenocarcinoma of the small intestine in sheep and from various metastases. Several cell types grew, most being fibroblastic in nature. However, 2 cultures yielded mixed cells which arranged themselves into areas of epithelial-like cells surrounded by fibroblast-like cells and this pattern was consistent over 30 subcultures and several months of culturing. The epithelial-like cells were separated from the others by the use of a modified medium containing citrulline or by sedimentation through a bovine serum albumin solution. Various properties, including their growth rate in 5% and 0.5% serum, the absence of surface fibronectin and their ability to grow in semi-solid agar, indicated that they may represent carcinoma cells. Screening for virus production from these cells and all other explant cultures proved negative.

Regeneration of wool follicles in autografts of sheep skin.

Three experiments involving six sheep were carried out at three different times in the annual wool growth cycle. Forty-eight full-thickness fitted autografts were sampled 2 h, 6 h, 24 h, 48 h, 3, 4, 5, 7, 9, 11, 14, 21 and 28 days after grafting. The histopathology of the grafts is described. Individual variation in 'take' was probably related to the speed with which vascular integrity was reestablished between graft and bed. Delayed acceptance caused the death of pilosebaceous units. In a successful graft, wool follicle regeneration appears to occur in three main ways: (1) an inactive follicle regenerates from the dormant bulb at about seven days, (2) follicles that were active at the time of grafting have first to form a papilla stalk, and such follicles did not become active until 11 days, (3) sometimes one or more outgrowths appeared at higher levels suggesting follicle regeneration by branching. In addition there were a few instances of de novo downgrowth of follicle plugs from the epidermis. Wool growth on the graft therefore arises almost entirely from the reorganisation of preexisting follicles.

Tumours of the upper alimentary tract.

Tumours of the oropharynx of domestic animals are common in most parts of the world, but squamous cell carcinoma of the upper alimentary tract shows differences in prevalence in different geographical areas and occurs at different sites in the various species. Oral tumours of the melanogenic system are more common in dogs than in man. The following main histological categories, which broadly correspond to those used in the classification of tumours of man, are described: papilloma; squamous cell carcinoma; salivary gland tumours; malignant melanoma; tumours of soft (mesenchymal) tissues; tumours of the facial bones; tumours of haematopoietic and related tissues; and odontogenic tumours and jaw cysts. Papilloma, squamous cell carcinoma, malignant melanoma, fibroma, and fibrosarcoma account for about 80% of the tumours that occur in the upper alimentary tract of domestic animals.

Tumours of the lower alimentary tract.

THIS CLASSIFICATION IS PRESENTED IN TWO PARTS: (a) tumours of the gastrointestinal tract; and (b) tumours of the anal canal and margin. In the gastrointestinal tract the tumours are classified as adenoma, adenocarcinoma, and undifferentiated carcinoma, with several subtypes. Most polyps prove to be non-neoplastic, hyperplastic, or regenerative rather than adenomatous. Carcinoma of the stomach occurs mainly in dogs, but is a rare tumour in all parts of the world. Moderately differentiated, tubular adenocarcinoma of the small intestine with excessive fibrosis occurs in all six species; in some geographical locations it may occur frequently in sheep and cattle. The adenoma/carcinoma sequence in the rectum of the dog is similar to that in man but is encountered less often. Carcinoid tumours are very rare in domestic animals. Among the soft tissue tumours, those of smooth muscle and adipose tissue are found fairly frequently and congenital mesothelioma in the peritoneum of calves occurs occasionally. Tumours of the haematopoietic and related tissues are the most common gastrointestinal neoplasms in all species and most belong to the lymphosarcoma group. Tumours of the anal canal and margin are common in the dog and 90% of these are tumours of the hepatoid (perianal) glands.

Tumours of the lung.

Lung tumours are not common in domestic animals; there has not been the increase in epidermoid carcinomas and anaplastic small-cell carcinomas that has occurred in man this century. Adenocarcinoma is the most common type in animals. The biological behaviour of each type of tumour in animals seems to be much the same as in man. The tumours are described histologically, the main categories being: epidermoid carcinoma, anaplastic carcinoma, adenocarcinoma, combined epidermoid and adenocarcinoma, carcinoid tumours, bronchial gland tumours, benign tumours, and sarcomas.