CUTANEOUS LYMPHOSARCOMA

General Considerations

•B cell or mixed cutaneous LSA that can either be primary or multicentric LSA

•no breed or site predilection

•single or multiple lesions with plaque, pustule, or ulcerative skin disease and resultant pruritis

•nodules with thick crust and underlying ulceration and erythematous rim

Treatment

•surgical resection ± systemic chemotherapy

Prognosis

•response to chemotherapy is usually poorer than multicentric LSA

•mycosis fungoides and cutaneous LSA in cats is associated with very poor prognosis as response to therapy is rare

MYCOSIS FUNGOIDES

General Considerations

•T cell cutaneous LSA

•breed predisposition: Poodle and Cocker Spaniel

•mycosis fungoides has been reported in cats

•site: epidermis, superficial dermis, and periadnexa (= epidermotrophic)

•gross appearance: plaque or nodular lesion

Clinical Signs

•protracted clinical course with 3 clinical stages:

•premycotic (erythroderma) stage: eczema, erythema, pigmentation or depigmentation, telangiectasis, atrophy, alopecia, and variable pruritis with trunk or neck involvement initially ± primary mucocutaneous junction or entire body involvement

•mycotic (plaque) stage: erythematous, raised, thickened, and firm plaques that may be ulcerative and exudative

•tumor stage: proliferative, protruding nodules ± ulceration and metastasis to regional lymph nodes and internal organs

•secondary pyodermas and lymphadenomegaly secondary to chronic dermatitis is common

Sezary Syndrome

•leukemic variant of mycosis fungoides characterized by circulating malignant helper T cells

•mycosis fungoides complicated by Sezary syndrome is characterized by splenomegaly, lymphadenopathy, and cyclic episodes of generalized erythroderma

•Sezary cells are identified in the peripheral blood of 100% of humans in the premycotic stage and 40% of the mycotic and tumor stages

•bone marrow does not become infiltrated with neoplastic cells in either mycosis fungoides or Sezary syndrome

Diagnosis

•biopsy although premycotic and mycotic stages are more reliable than tumor stage

Treatment

•no uniform success with multiple treatment regimens

•lesions limited to the skin can be treated with:

•topical nitrogen mustards (i.e., mechiorethamine or BCNU)

•vitamin A analogues (i.e., 13-cis-retinoic acid)

•electron radiation therapy

•photodynamic therapy (with psoralen UVA)

•intravenous and intralesional fibronectin (acts as opsonin in areas of disrupted tissue and chemotactically draws macrophages into tissue)

•intradermal placental lysate

•prednisone

•systemic chemotherapy should be attempted with disseminated mycosis fungoides but results are usually poor

Prognosis

•poor with most animals euthanased prior to tumor stage development due to uncontrollable skin lesions