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Feline paraneoplastic alopecia

by
01 September 2016, at 1:00am

David Grant continues his series looking at dermatological conditions.

  • Rare and unique to the cat (Miller and others, 2013). Can be considered a cutaneous marker for an underlying malignancy (Hnilica, 2011). 
  • Associated in most cases with a pancreatic malignant tumour, either acinar or pancreatic duct. In these cases metastasis has often occurred at the time of diagnosis. Bile duct carcinoma has also been described, and most recently a single case was reported of a metastasising intestinal carcinoma (Grandt and others, 2015). 
  • Occurs often in cats older than 10 years. 
  • No sex or breed predilection. 

Clinical signs

  • Rapid in onset (weeks to a few months). 
  • Alopecia begins ventrally and then spreads to the limbs, sparing the head in most cases.
  • Focal areas of erythema with a characteristic shiny and glistening skin. 
  • There may be crusting and waxy debris associated with secondary Malassezia, leading to pruritus. 
  • Loss in weight and general signs of illness associated with the underlying malignant tumour.

Differential diagnosis

(Hnilica, 2011)

  • Hyperadrenocorticism. 
  • Fleabite hypersensitivity. 
  • Dermatophytosis. 
  • Food allergy. 
  • Cutaneous drug eruption. 
  • Telogen de uxion. 
  • Alopecia areata. 

Diagnosis

  • History, physical examination. The distinctive appearance of the signs in an older cat, which are sudden in onset and with easy epilation of the skin, are all highly suggestive. 
  • Rule-out of differentials. 
  • Skin biopsy. Acanthosis, parakeratosis, follicular atrophy and lack of trichilemmal keratin (Miller and others, 2013). 
  • Radiography and ultrasonography may enable a diagnosis, but not always as masses may be too small to visualise. 
  • Exploratory laparotomy.

Treatment

  • Appropriate treatment of secondary pyoderma and Malassezia dermatitis to control pruritus. 
  • Supportive care.
  • Complete removal of an underlying malignant tumour would be the theoretical treatment of choice. Curative surgery has not been reported although there was a temporary improvement in one cat before return of clinical signs with tumour recurrence (Tasker and others, 1999).

Prognosis

  • The prognosis is very poor as many underlying tumours have metastasised by the time the diagnosis is made. 
  • Most cases die within eight weeks of diagnosis with euthanasia frequently necessary.
  • Illustrations by courtesy of David Lloyd, Royal Veterinary College Dermatology Group.

References and further reading 

  • Grandt, L-M, Shroeder, S., Kochlerk, K. and others (2015) Feline paraneoplastic alopecia associated with metastasizing intestinal carcinoma. Journal of Feline Medicine and Surgery1 (2). 
  • Hnilica, K. A. In: Small Animal Dermatology – A Color Atlas and Therapeutic Guide, 3rd edition, pp304-309. Elsevier, 2011. 
  • Miller, W. H., Grif n, C. G., Campbell, K. A. In: Muller and Kirk’s Small Animal Dermatology, 7th edition, pp568-569. Elsevier, 2013. 
  • Tasker, S., Griffon, D. J., Nuttall, T. J. and others (1999) Resolution of paraneoplastic alopecia following surgical removal of a pancreatic carcinoma in a cat. Journal of Small Animal Practice 40 (1): 16-19.