Small Animal Dermatology, 3rd edition

382 DISEASES/DISORDERS

CLINICAL FEATURES

 Cutaneous histiocytoma:
Solitary cutaneous mass; may be multiple (<1% of cases) especially in the

Chinese shar pei (Figure 25.1)

Dome-shaped, erythematous and alopecic nodule (“button cell tumor”) (Figures

25.2, 25.3)

Usually less than 2 cm diameter

Predominantly develop on head, pinnae, limbs

Rapid development (days to few weeks)

Occasional regional lymph node involvement

Majority of cases spontaneously resolve within 3 months.

 Reactive cutaneous histiocytosis:
Multiple dermal and subcutaneous, erythematous nodules or plaques (Figure

25.4)

Nodules/plaques may be alopecic or ulcerated (Figure 25.5)

Nodules range in size from 1 to 5 cm

Not pruritic or painful

Number of lesions variable: may range from few to hundreds

Occur most frequently on the head, neck, perineum, scrotum, and extremities

(Figure 25.6)

Tend to wax and wane

Nasal mucosa involvement may occur (producing a “clown nose”)

Systemic and lymph node involvement does not occur in this form.

 Reactive systemic histiocytosis:
Cutaneous manifestations identical to reactive cutaneous histiocytosis:
Multiple, nodular, and well circumscribed (Figure 25.7)
Often ulcerated, crusted, or alopecic
Often extend into the subcutis
Occur most frequently on the muzzle, nasal planum, eyelids, flank, and
scrotum (Figure 25.8)
Not painful or pruritic
Ocular manifestations:
Conjunctivitis
Chemosis
Scleritis
Episcleritis
Episcleral nodules
Corneal edema
Anterior and posterior uveitis
Retinal detachment
Glaucoma
Exophthalmos
Lethargy
Anorexia