Pedal mass in a crossbred dog Author: David GrantEditor: David Lloyd © European Society of Veterinary Dermatology

History | Signs | Differentials | Tests | Therapy | Notes Click to reveal the text on this screen Click the forward arrow to jump to the next screen History year-old entire female crossbred dog Weight 23 kg A lump had developed over a period of months on the right fore foot The dog was presented when the lesion became ulcerated and began to bleed History

History | Signs | Differentials | Tests | Therapy | Notes History - 2 The dog was lame on the affected foot but otherwise in good health History

History | Signs | Differentials | Tests | Therapy | Notes A mobile, ulcerated mass of 5 cm diameter was present over the third digit. It was not painful on palpation. There were no other lesions; no lymphadenopathy. Clinical signs - 1 Signs Lateral view of the mass

History | Signs | Differentials | Tests | Therapy | Notes How would you approach this case? Signs What are the next steps you would take? Make a list of your principle differential diagnoses List any samples you would collect List any tests you would perform to assist in making a definitive diagnosis

History | Signs | Differentials | Tests | Therapy | Notes Case investigation Differentials Principle differential diagnoses Neoplasia e.g. Schwannoma, haemangiopericytoma, fibroma, fibrosarcoma Bacterial pseudomycetoma Actinomycetosis, Nocardiosis, Eumyctic mycetoma Foreign body reaction

History | Signs | Differentials | Tests | Therapy | Notes Tests Surgical excision and histopathology were logical diagnostic and therapeutic steps

History | Signs | Differentials | Tests | Therapy | Notes Results Tests Histopathology (Joan Rest) Shows a mass of elongated cells in onion-skin patterns with moderate quantities of intervening collagen. Some nuclei are pallisaded. Other areas are looser in texture. Characteristic of a schwannoma. Where an edge is present there is a well- defined border.

History | Signs | Differentials | Tests | Therapy | Notes What is your diagnosis? Do the investigations permit a definitive diagnosis? Are there any additional investigations which you think may need to be done? Tests

History | Signs | Differentials | Tests | Therapy | Notes Diagnosis Schwannoma Tests

History | Signs | Differentials | Tests | Therapy | Notes Prognosis Prognosis is quite good Tumour not attached to subjacent tissue No evidence of local spread Histology does not suggest malignancy But little skin available locally to facilitate removal Tests

History | Signs | Differentials | Tests | Therapy | Notes How would you deal with this case? Should preliminary cytology have been done? Is surgical excision wise as an initial procedure? Therapy

History | Signs | Differentials | Tests | Therapy | Notes Therapy - 1 Therapy Justification for immediate excision Lesion characteristic of neoplasm, clinically Dog in pain If an infection, surgery would still be necessary Good prognosis if complete removal possible Although schwannomas may recur after excision; they do not metastasize Warning: limb amputation could be necessary ultimately

History | Signs | Differentials | Tests | Therapy | Notes Response to surgery Notes Complete removal and coaption was possible giving a good cosmetic result as seen here after 10 days No recurrence after 1 year

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