Clinical approach to tumors of the skin and subcutaneous tissues

With skin tumors, "a lump is only a lump" until a definitive diagnosis has been made. It is nearly impossible to make an accurate diagnosis solely on clinical signs. In some instances, fine-needle aspirate may be diagnostic; however, in all instances biopsy is the preferred method for definitively diagnosing canine and feline skin tumors. Prognosis and treatment depend on the diagnosis.     

Comparison of the role of the subcutaneous tissues in cutaneous wound healing in the dog and cat

Objective— To describe and compare the contribution of the subcutaneous tissues to 1st and 2nd intention cutaneous wound healing in the dog and cat.
Study Design— Experimental study.
Animals— Domestic shorthaired cats (n=6) and 6 beagle dogs.
Methods— Paired wounds were created on either side of the dorsal midline; the subcutaneous tissue was removed on 1 side and left intact on the other. Square, open wounds of the dorsal aspect of the thorax were observed for 21 days to monitor granulation tissue formation, wound contraction, epithelialization, and total healing (contraction+epithelialization). Breaking strength of sutured linear wounds was measured 7 days after wounding. Laser-Doppler perfusion imaging (LDPI) was used to measure cutaneous perfusion.
Results— First intention healing: subcutaneous tissue removal had no consistent effect on sutured wound strength at 7 days in dogs or cats. Second intention healing: removal of subcutaneous tissue reduced wound perfusion, granulation, contraction, epithelialization, and total healing. Granulation tissue formation and wound contraction were delayed to a significantly greater degree in cats than in dogs ( P <.05). Two dogs (33%) had minor wound infections.
Conclusions— The subcutaneous tissues make an important contribution to 2nd intention cutaneous healing. Dog and cat wounds had delayed 2nd intention healing when subcutaneous tissues were removed; wounds in dogs, but not cats, had largely recovered from this delay by 21 days.
Clinical Relevance— Extensive debridement of subcutaneous tissue may delay wound healing particularly in feline patients. A higher risk for wound infections may accompany extensive removal of subcutaneous tissues in dogs.     

Thyroid tumours in the dog

The clinical, radiological and histopathological features of 30 thyroid tumours in the dog are described. Ten tumours were considered suitable for surgical removal and in a follow-up period of between 14 and 36 months five dogs were still alive.     

Immunocytochemical diagnosis of skin tumours of the dog with special reference to undifferentiated types

Immunoperoxidase techniques for S-100 protein, keratin, cytokeratin, vimentin and desmin were applied to 65 canine skin tumours. These included eight squamous cell carcinomas, eight fibrosarcomas, eight melanomas, eight mastocytomas, eight haemangiosarcomas, eight leiomyosarcomas, five liposarcomas and 12 poorly differentiated tumours. Consistent results were obtained within each group. Cytokeratin and keratin immunoreactivity was detected only in squamous cell carcinomas. Vimentin was present in fibrosarcomas, melanomas, haemangiosarcomas, mastocytomas, leiomyosarcomas and liposarcomas. S-100 protein immunoreactivity was detected in melanomas, haemangiosarcomas, liposarcomas and leiomyosarcomas. Only leiomyosarcomas were positive for desmin. According to these results the 12 anaplastic tumours were diagnosed either as carcinomas, fibrosarcomas or malignant melanomas.     

Primary and secondary bone tumours in the dog

During a 14-year period (January 1962 to December 1975), 394 primary and secondary tumours or tumour-like lesions affecting bones were diagnosed in the dog. The most frequently occurring tumour was osteosarcoma (183, 46.5%), followed by chondrosarcoma (forty-four, 11.2%), squamous cell carcinoma (thirty-nine, 10%), fibrosarcoma (thirty-one, 7.8%), multiple myeloma (fourteen, 3.6%), haemangiosarcoma (fourteen, 3.6%), malignant melanoma (thirteen, 3.3%), synovioma (nine, 2.3%), lymphosarcoma (eight, 2.0%), cartilage analogue of fibromatosis (seven, 1.8%), adaman-tinoma (five, 1.3%), osteocartilaginous exostosis, ossifying fibroma, rhabdomyosarcoma (four each), polyostotic cyst, haemangiomatosis (three each), odontoma, tumoral calcinosis (two each), and osteoma, chondroma, desmoid fibromatosis, and malignant mesenchymoma (one each).
Of these, desmoid fibromatosis, malignant mesenchymoma, and haemangiomatosis have not been previously reported in the dog.     

Nerve sheath tumours in the dog and cat

Schwannomas were diagnosed in twelve dogs and five cats at Massey University Small Animal Clinic and Hospital over a 15-year period (1977-92). A further two feline cases were reported at the Batchelar Animal Health Laboratory. In six dogs, the tumour involved nerves of the brachial plexus. Clinical signs observed in these dogs were forelimb lameness, muscle wasting and pain on movement of the affected limb or neck. Hindlimb paresis was observed in two dogs. Surgical excision of the brachial plexus tumour was attempted in one dog, leading to an 8-month remission of signs. In one dog, the tumour involved the sacral nerves, and in two dogs the cranial nerves were affected. Three dogs had skin nodules. Seven of the twelve affected dogs were destroyed. In five cats, the tumours developed on the carpus, tarsus or interdigital area of a forelimb or hindlimb as a slowly developing nodular lesion. In the other two cats, the site of the tumour was the flank and the lateral thigh respectively. Surgical excision of the tumour was successful in three cats.     

Hormone producing ovarian tumours in the dog

In two cases of granulosa cell tumours of the ovary in bitches there was production of sex hormones by the neoplasm. Both tumours produced oestrogens but one also produced significant concentrations of progesterone. In both bitches, the presenting sign was abnormally prolonged oestrus activity. One dog also developed a haemorrhagic diathesis as a result of endogenous oestrogen toxicity.     

Secondary bone tumours in the dog.

During a 2 1/2-year period 209 dogs with 218 malignant tumours were examined for skeletal metastases. There were 77 malignant tumours without visceral or skeletal metastases. Twenty-four (17%) of the 141 tumours with visceral metastases also had skeletal metastases. Ninety-eight of these tumours were of epithelial origin, and of these 21 (21.4%) had skeletal metastases. In 14 dogs, more than one bone had a metastatic tumour. The humerus, femur and vertebral column were most frequently involved. The lung was the most frequent site of metastatic tumours; then, in order, the liver, kidney and skeleton. The incidence of primary and secondary bone tumours was similar. Metastatic bone disease in the dog is far more common than is generally realized.     

Cytologic features of testicular tumours in dog

In this paper, we report on our experience of cytology of fine needle biopsies performed on 92 dogs with testicular tumours during the period from 1998 to 2002. Cytological diagnosis was consistent with seminoma in 20 cases, sertolioma in 16 cases, Leydig cell tumours in 50 cases and mastocytoma in one case. Five cases could not be diagnosed by cytology. Cytological observations were confirmed after surgery by histopathological examination in 87 cases. Cytology provided a sensitivity of 95% for seminoma, 88% for sertolioma and 96% for Leydig cell tumours. The specificity was 100% for all three tumour types. In our experience cytology of fine needle aspirations of testicular tumours is a very reliable technique.     

Anaplastic and aggressive subcutaneous sarcoma in a seven-month-old dog

A seven-month-old female, Italian hound which was presented with anorexia, dyspnoea and weight loss showed two subcutaneous masses at physical examination. Radiographs showed multiple opacities in the lungs, thorax, liver and spleen, and cytology showed discrete pleomorphic cells, with variable nuclear : cytoplasmic ratio, foamy cytoplasm and round to oval nuclei. Incisional biopsy histology showed the infiltrative proliferation of highly pleomorphic spindle to roundish large cells, discrete or arranged in a storiform pattern, with scattered multinucleated giant cells. Immunohistochemistry exhibited strong positivity for vimentin and mild labelling for alpha-smooth muscle actin and lysozyme; other mesenchymal or histiocytic lineage markers stained negatively. Because of the poor prognosis, the owner elected euthanasia. Post-mortem examination confirmed massive metastatic spread. Cytology, histology and immunohistochemistry suggested the diagnosis of anaplastic sarcoma with giant cells, although disseminated histiocytic sarcoma was a reliable differential diagnosis. The authors underline the difficulties in definitively categorising poorly differentiated sarcomas, even if a large panel of markers is applied.     

Histologic and immunohistochemical characterization of thymic epithelial tumours in the dog

Thymic epithelial tumour (TET) histologic subclassification has not been well described in the veterinary literature as it has in humans. The objective of this study was to identify and describe TET subtypes in dogs and to determine the utility of immunohistochemistry (IHC) in differentiating these subtypes. Samples were reviewed and classified according to a modified World Health Organization (WHO) criteria for human tumours of thymic origin. Signallment, presenting signs, treatment and survival data was collected from medical records. Histologic review confirmed the same subtypes as described in humans. Presence of high stage disease, pleomorphism, mitotic figures and capsular invasion was more common in atypical thymomas and thymic carcinomas than in thymomas. IHC was performed for GLUT‐1, CD5, CD117 and CK8/18; however, this was not useful in classifying the tumours.     

Cytology of subcutaneous glandular tissues.

This article deals with the cytologic appearance of various glandular tissues located in the subcutaneous tissues. Normal cytologic features are described. In addition, inflammatory, infectious, neoplastic, and hyperplastic changes are discussed. Most of these features are depicted in the 60+ photomicrographs that are distributed throughout the article. Many of the changes are similar in the glands, and it is usually possible to differentiate the gland of origin based on cytologic appearances. Subcutaneous neoplasms that are not associated with a subcutaneous gland, and lymph node cytology are not covered in this article but are addressed elsewhere.     

Intra-nasal tumours in the dog: an evaluation of prognosis

The case records and owners of twenty–nine dogs with intra–nasal neoplasms seen at the University of Pennsylvania were investigated. Fifteen dogs were treated surgically of which thirteen were euthanized within 4 months of treatment and two were lost to follow–up. Earlier surgical treatment based on present diagnostic methods appeared not to improve the prognosis. Four dogs were treated with radiation and survived for 6, 12, 26 and 52 months from the initial treatment. At present, radiation therapy, whilst only palliative, offers the best results. Résumé. On a étudié les protocoles d'observation chez vingt-neuf chiens avec des néoplasmes intranasaux examinés à l'Université de Pennysylvanie et on a interrogé leurs propriétaires. Quinze chiens ont été traités par chirurgie, treize d'entre eux ont dǔ ětre détruits en quatre mois de traitement et tout contact a été perdu avec les deux autres pour les soins post-opératoires. Un traitement chirurgical antérieur, basé sur des méthodes actuelles de diagnostic ne semble pas avoir perfectionné le prognostic. Quatre chiens ont été traités par radiations et ils ont survécu pendant 6, 12, 26, et 52, mois à partir du traitement initial. Pour le moment, la thérapeutique par radiations, bien que palliative, offre les meilleurs résultats. Résumé. Die Krankenbefunde und die Besitzer von neunundzwanzig Hunden mit intra-nasalen Neoplasmen die man an der Universitàt von Pennsylvanien behandelte, wurden erforscht. Fùnfzehn Hunde wurden chirurgisch behandelt, von denen man dreizehn innerhalb von vier Monaten der Behandlung mit Euthanasie aus dem Leben half, von den ǔbrigen zweien verlor man jede Spur zur Nachforschung. Friihere chirurgische Behandlung auf gegenwǎrtige diagnostische Methoden beruhend, schien die Prognose nicht zu verbessern. Vier Hunde wurden durch Bestrahlung behandelt und uberlebten 6, 12, 26 und 52 Monate vom Beginn der anfang-lichen Behandlung. Zur Zeit beitet Bestrahlungstherapie obwohl nur palliativ, die besten Ergebnisse.