“Lisa” is a 14 yr FS DSH that presented with a 18-24 month history of hair loss on the muzzle, progressing to involve the pinnae and the nose itself appeared swollen. No response was noted to cefovecin (8 mg/kg SQ). “Lisa” was indoor-only with no travel history outside of the San Francisco area, and aside from mild chronic kidney disease was reportedly healthy without other medical concerns.
Christie Yamazaki DVM, DACVD
Dermatology For Animals, Oakland, CA
June 2024
History
“Lisa” is a 14 yr FS DSH that presented with a 18-24 month history of hair loss on the muzzle, progressing to involve the pinnae and the nose itself appeared swollen. No response was noted to cefovecin (8 mg/kg SQ). “Lisa” was indoor-only with no travel history outside of the San Francisco area, and aside from mild chronic kidney disease was reportedly healthy without other medical concerns.
Exam
Weight: 3.5 kg (7.6 lb)
Temp: 102.1 F (rectal)
Pulse: 220 bpm
Resp: 28 bpm
Dermatologic physical examination: BARH, BCS 4/9. There was an annular area of alopecia, mild thickening and mild dry scale with patchy erythema and excoriations on the concave and convex aspects of the medial border of the right helix/pinna as well as left cutaneous marginal pouch. The rostral muzzle at the level of the planum nasale appeared edematous with moderate erythema, hypopigmentation and hypotrichosis progressing caudally. There was no loss of or change to cobblestone texture of the nasal planum itself. The paws, mucous membranes, trunk all appeared unremarkable and unaffected.
Differential diagnoses included lymphocytosis, sarcoidosis, pemphigus foliaceus, dermatophytosis, mosquito bite hypersensitivity.
Diagnostics
Skin cytology of the dorsal muzzle and right medial helix of pinna revealed abundant atypical round cells with anisocytosis and anisokaryosis, cytoplasmic vacuolation. A sedated biopsy was performed of the pinnae, haired skin on dorsal muzzle and nasal planum.
Histopathology findings included nodular sheets of monomorphic small lymphocytes that expanded the dermis, extending down to adnexa with small clusters in the epidermis and follicular epithelium. The cells had small variably distinct cell borders, scant light basophilic cytoplasm, oval nuclei, clumped chromatin and indistinct nucleoli. There was no lymphovascular invasion.
Assessment
The findings were consistent with feline cutaneous lymphocytosis, which is also referred to as pseudolymphoma.
Treatment Plan
“Lisa’s” owner elected to start with modest corticosteroid therapy and pending response were open to dose adjustment +/- chlorambucil.
Follow-up
At time of publication, “Lisa” had been on methylprednisolone 1.1 mg/kg per os q 48 hr and reportedly feeling well with minimal polyphagia/polydipsia and had reduction of the swelling noted to the nose as well as crusting to the pinnae.
Discussion
Feline cutaneous lymphocytosis is a relatively uncommon condition secondary to an accumulation of lymphocytes in the skin that generally affects older female cats. Etiology is unknown, but it is suggested that this is a reactive process in cats. Presenting as solitary, alopecic, erythematous ulcerated or excoriated lesions, the most common locations include the thorax, legs and pinnae, flank and neck. Generally onset is acute with slow progression and lesions can range from 1.5 cm to 10 cm. Diagnosis requires histopathology.
Cutaneous lymphocytosis seems to be a relatively benign or protracted disease in cats, similar to pseudolymphoma reported in humans. Some cases have been noted to undergo malignant transformation but generally this disease runs an indolent but benign course with treatment and most cats do not become systemically ill.
Treatment is variable, with options commonly including corticosteroids and chlorambucil. Overall, cats have a long median survival time regardless of treatment received.
References
- Miller WH, Griffin CE, Campbell KL. Neoplastic and Non-Neoplastic Tumors: Feline Cutaneous Lymphocytosis. Muller and Kirk’s Small Animal Dermatology. 7th Philadelphia, PA: Saunders, 2013; 816-817.
- Pariser M, Gram D. Feline cutaneous lymphocytosis: case report and summary of the literature. Journal of Feline Medicine and Surgery. 2014; 16(9): 758-763.
- Albanese F, et al. Feline and canine Cutaneous Lymphocytosis: Reactive Process or Indolent Neoplastic Disease? Vet Sci. 2022 Jan 11; 9(1): 26.
Search terms
lymphocytosis cat, immune mediated hemolytic anemia, chronic lymphocytic leukemia, cytotoxic t cells, neoplastic cells, bone marrow, b cells, natural killer cells, acute lymphoblastic leukemia, feline leukemia virus, antigen receptor rearrangement, peripheral blood, feline immunodeficiency virus, lymph nodes, t cells, circulating lymphocytes, flow cytometry, veterinary medicine, helper t cells, lymphocyte counts, circulating neoplastic cells, normal lymphocytes, clinical findings, prolonged survival, lymphoid tissue, treatment protocols, polymerase chain reaction, clinical outcome, cell lymphoma, clinical signs, severe combined immunodeficiency, plasma cells, lymphoid leukemia, clinical presentation, acute leukemia, dogs and cats, mast cells, viral infection, bacterial infections, blood vessels, pcr for antigen receptor, t lymphocytes, blood samples submitted, vet intern med, double negative, blood smear, clonal expansion, young animals, neoplastic lymphocytosis, blood samples, cats treated, retrospective study, rarely observed, veterinary clinics, prognostic factors, ehrlichia canis infection, peripheral lymphocytosis, hematologic abnormalities, outcome cohort, healthy cats, laboratory findings, blood collection, epinephrine mediated lymphocytosis, large lymphocytes, outcome data, veterinary hematology, mild lymphocytosis, hematologic findings, infectious agents, healthy animals, clonality testing, immunophenotypic characterization