Conference 13 - 2009 Case: 01 20100127

Signalment:

11-year-old, castrated male, chinchilla longhair cat (Felis catus).Presented with skin disease, weight loss, and polydypsia. Ultrasound revealed an abnormal pancreas, a nodular liver and congenital absence of the right kidney.

Gross Description:

The cat was in poor condition and weighed 3.6 kg. Extensive alopecia was noted over the muzzle and periorbital areas, all four limbs, the thorax, on the ventrum and in the axillary and inguinal regions. Over the axillary and inguinal regions and plantar aspects of the carpus, metacarpus, tarsus and metatarsus, there were focally extensive erosions. Hyperpigmentation was present in the alopecic areas of the muzzle and periorbita. A paucity of subcutaneous and intra-abdominal fat was noted.

Diffusely the lungs were dark, red and heavy. The cut surface was similar and 100% of the lung was involved. The pericardial sac contained 10 mL of red fluid and diffusely there was minimal nodular thickening of the left atrioventricular valve.

Multifocally on the capsular and cut surface of the liver were numerous (approximately 10) raised, well-demarcated, yellow-white, soft, round nodules that were variably sized, ranging from 0.5 to 2 cm in diameter. Diffusely the pancreas was mottled dull grey-red and contained numerous raised, firm, round nodules that were up to 0.5 cm in diameter. Focally at the body of the pancreas, there was a larger, raised, poorly demarcated, yellow-white, firm, nodular mass that was 2 cm in diameter. The left kidney measured 42 x 30 x 20 mm and appeared normal. The right kidney and ureter were not present.

Morphologic Diagnosis:

Skin: Dermatitis/cellulitis, chronic-active, diffuse, moderate with hair follicle and sebaceous gland atrophy and moderate epidermal hypoplasia and hypokeratosis.

Lab Results:

Bacterial culture of the liver revealed no significant growth.

Condition:

Feline paraneoplastic alopecia

Contributor Comment:

A diagnosis of feline paraneoplastic alopecia (FPA) was reached after postmortem diagnosis and histopathology revealed a pancreatic exocrine adenocarcinoma, which had metastasized to the liver. Changes in the hair follicles and dermis are characteristic of those reported for FPA. Feline paraneoplastic alopecia usually starts on the ventral neck, thorax or abdomen, the changes grossly apparent as a non-pruritic, progressive, symmetrical alopecia. Hairs are easily epilated and the skin is thin, shiny and inelastic. Footpad involvement has also been reported, with varying presentations from dry and cracked to moist, erythematous pads. These are usually painful. The cause of the alopecia is not fully understood and it is non-responsive to corticosteroid treatment. When the carcinoma was surgically excised the condition resolved in one case, although it did recur at the time of metastasic tumour recurrence.(4) Most affected cats are reported to groom excessively, and it has been postulated that the shiny appearance of the skin arises from the resulting exfoliation of the stratum corneum.(3) Affected animals range in age from 7-16 years (median 13 years), with no apparent breed predilection.(5) Skin lesions are often accompanied by other systemic clinical signs, such as weight loss, vomiting, diarrhea, anorexia and lethargy. This disease has been reported with pancreatic carcinoma in 12 cats and biliary carcinoma in two cats.(5)

Histopathological examination of the skin consistently shows a non-scarring alopecia with characteristic marked follicular telogenization, miniaturization and atrophy, with similar adnexal atrophy. Other findings include mild epidermal acanthosis and hyperplasia with a hypo- or non-keratinized epidermis, and a mild, mixed, perivascular inflammatory infiltrate of the dermis, consisting of lymphocytes, macrophages and neutrophils.(3,4) In a recent report of feline skin biopsies complicated by Malassezia spp., histopathology from 7 of 15 cases was consistent with FPA. Although pancreatic carcinoma was confirmed in only four of these cats, it is possible that an indication of internal malignancy could be made when Malassezia spp. are detected in histopathology of cats with generalized skin disease.(2)

Neoplastic diseases of the exocrine pancreas and biliary tree are rare in the cat. The prognosis for these is generally poor since at the time of diagnosis the disease has often metastasized to distant sites, such as the liver, lymph nodes and lungs, as well as possibly local seeding to intraperitoneal sites. Twelve of the fourteen cats reported in the literature died or were euthanized within 8 weeks of onset of clinical signs.

JPC Diagnosis:

Haired skin and subcutis: Follicular atrophy, diffuse, marked, with mild, multifocal, lymphoplasmacytic and histiocytic dermatitis.

Conference Comment:

The sections of haired skin from this cat contain the histologic features of FPA, including profound follicular atrophy with sparing of the sebaceous glands and acanthosis. Additionally, the presence of a pancreatic adenocarcinoma supports a diagnosis of FPA. However, the moderator and several conference participants identified other histologic features not typical of FPA, including: small areas of epidermal necrosis and/ or individual cell necrosis in the epithelium in some slides; subepidermal clefting; congested small blood vessels in the superficial dermis; and ulceration in a few sections. Conference participants debated whether the subepidermal clefting was real or artifact, and suggested that additional history may be helpful in identifying other factors to explain the clefting and epithelial necrosis.

Differentiation between FPA and feline hyperglucocorticoidism (FHG) was discussed. Follicular atrophy is present in both conditions, but it is more striking in FPA and hair follicles in FHG have increased tricholemmal keratinization (bright eosinophilic core in an atrophic follicle) and follicular hyperkeratosis. Sebaceous glands may be atrophied in FHG, but are usually normal in FPA. The most striking feature of FHG is profound dermal atrophy, whereas the dermis is normal in FPA. FPA is also characterized by acanthosis with parakeratotic hyperkeratosis.(1)

In addition to FPA, other paraneoplastic skin lesions include feline thymoma-associated exfoliative dermatitis, nodular dermatofibrosis, feminization syndrome associated with Sertoli cell tumors, superficial necrolytic dermatitis and paraneoplastic pemphigus, all of which are described in an excellent review article.(5) Nodular dermatofibrosis occurs primarily in the German Shepherd Dog and is associated with renal cystadenomas or cystadenocarcinomas and uterine leiomyomas.(5) Superficial necrolytic dermatitis occurs more commonly due to hepatopathy or diabetes mellitus, but it has also been associated with a glucagonoma.(5) Paraneoplastic pemphigus is extremely rare.

References:

1. Gross TL, Ihrke PJ, Walder EJ, Affolter VK: Skin Diseases of the Dog and Cat: Clinical and Histopathologic Diagnosis, 2nd ed., pp. 498-501. Blackwell Publishing, Ames, IA, 2005
2. Mauldin EA, Morris DO, Goldschmidt MH: Retrospective study: the presence of Malassezia in feline skin biopsies, a clinicopathological study. Vet Dermatol 13:7-13, 2002
3. Pascal-Tenorio A, Olivry T, Gross TL, Atlee BA, Ihrke PJ: Paraneoplastic alopecia associated with internal malignancies in the cat. Vet Dermatol 8:47-52, 1997
4. Tasker S, Griffon DJ, Nuttall TJ, Hill PB: Resolution of paraneoplastic alopecia following surgical removal of a pancreatic carcinoma in a cat. Jour Small Anim Pract 40:16-19, 1999
5. Turek MM: Cutaneous paraneoplastic syndromes in dogs and cats: a review of the literature. Vet Dermatol 14:279-296, 2003