Non Neoplastic - Cutaneous Diseases: Cutaneous Lymphocytosisand Cutaneous Reactive Histiocytosis

CUTANEOUS LYMPHOCYTOSIS:

Cutaneous lymphocytosis (CL) was originally classified as a reactive lympho-proliferative disease, and was sometimes referred to as a “pseudo-lymphoma”. However, it has now been characterized immunohistochemically – in both dogs and cats – as an indolent (slowly progressive) form of cutaneous T-cell lymphoma (CTCL). 1,2 In this regard, it is a true neoplasm with malignant potential and may develop an aggressive biological behavior over time. CL is a rare disease in dogs and only moderately more common in cats.

In a series of 23 feline cases 1 , CL predominantly affected older cats (mean age at diagnosis = 12.3 years). Lesion were often solitary and characterized by some combination of alopecia, erythema, scale, and erosion/ ulceration. Less common lesions included plaques, nodules, and miliary papules. The body site most commonly affected was the lateral thorax although many other areas were reported, including footpads and nasal planum. Pruritus was common, although the behavior of the lesions was relatively benign compared to standard CTCL cases. Survival ranged from 6 to 59 months. A single case of spontaneous remission was documented. Anorexia and weight loss were noted in six cats and four underwent necropsy after euthanasia, which revealed lymphoma within visceral organs. Glucocorticoid therapy (orally, parenterally, or topically) was attempted in 18/23 cats with only 6 showing a good to excellent response. When either chlorambucil or lomustine was combined with an oral steroid, a good to excellent response was documented in 4/5 cats treated. […]