This 8-year-old neutered male domestic shorthaired cat has a two-month history of pruritic generalized crusting dermatitis that has been poorly responsive to antibiotics and bathing (Figure 1). Six weeks ago, a mediastinal thymoma was surgically removed; the crusting dermatitis preceded the surgery and persisted unchanged postoperatively.
Cytologic examination is performed on samples of exudate under pinnal crusts (Figure 2) and on moist crusts from the ventral trunk (Figure 3).
What is your tentative diagnosis?
a) Cutaneous lymphoma
b) Pemphigus foliaceus
d) Bacterial pyoderma
e) Thymoma-associated exfoliative dermatosis
f) Both B and D