Faecal Occult Blood Test

Case of the Month (Emma Scurrell June 2012)

Subungual melanoma in a dog

An 8-year-old male Rottweiler presented with swollen digit on the left frontleg and radiographs indicated lysis of the third phalanx (P3). Amputation of the digit was performed and submitted for histopathological evaluation. 

Fig 1. This is the gross specimen of the digit that has been sectioned longitudinally and reveals a destructive brown-black mass at the level of the nailbed which essentially replaces most of P3.

Fig 2. Histopathological evaluation confirms the presence of a malignant melanoma. Neoplastic melanocytes are highly pleomorphic, are variably well-pigmented and display a high mitotic rate. (H&E, x400)


Final Diagnosis

Subungual malignant melanoma


Subungual melanomas arise from the melanocytes of the nailbed. These tumours are usually slowly progressive and are commonly associated with invasion and lysis of P3 at the time of diagnosis. Breed predispositions include the Scottish terrier, Schnauzer, Rottweiler, Golden retriever and Irish setter. The major clinical differential is a squamous cell carcinoma which is the most common malignancy affecting the canine digit. Reported metastatic rates of subungual melanomas are reportedly higher than other cutaneous melanomas ranging from 38-58% with a 1-year survival rate of 42-70%. Another recent study reported a metastatic rate of 50% with a mean disease-free interval of 322 days.

Previous Monthly Cases

Hypertensive Retinopathy January 2010
FIP in a cat - uncommon presentation February 2010
Phaeohyphomycosis    March 2010 
Scleral Rupture April 2010
Canine and feline epulides May 2010
Erythema multiforme in a labrador retreiver June 2010
Keloidal fibrosarcoma in a labrador retreiver July 2010
Cutaneous epitheliotropic lymphoma  August 2010 
Benign cutaneous histiocytoma  September 2010 
Iridociliary adenoma October 2010
Proliferative thrombovascular necrosis of the pinnae November 2010
Signet-ring cell carcinoma in the stomach of a dog December 2010
Cutaneous infiltrative lipoma in a labrador January 2011

Tonsillar squamous cell carcinoma February 2011
Canine orbital meningioma March 2011
"Lung-digit" syndrome in a cat April 2011
Hepatic amyloidosis in a cat May 2011
Haemophagocytic histiocytic sarcoma June 2011
Alternaria spp. infection in an immunocompromised dog July 2011
Ocular manifestation of lymphoma in a cat  August 2011
Kerion dermatophytosis in a Cocker spaniel September 2011
Subcuticular coenurus in a rabbit  October 2011
Optic nerve glioma in a dog November 2011
Malignant transformation of a viral papilloma in a dog  December 2011
Uveodermatological syndrome in an Akita
January 2012
Cutaneous angiostomatosis in a dog  February 2012
Transitional cell carcinoma in a dog  March 2012
Corneal inclusion cysts in a dog   April 2012
Extraskeletal osteosarcoma in a dog  (May 2012)

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Faecal Occult Blood Test