Idiopathic lymphocytic mural folliculitis

From Felipedia

Lymphocytic mucinous degenerative mural folliculitis in a DSH cat. There is diffuse alopecia and intense scaling on the face, limbs and trunk^[1]

Same cat as above

Same cat as above

Feline lymphocytic mural folliculitis (Interface isthmus folliculitis, Pseudopelade) is a rare dermatological condition of cats which occurs worldwide. Histologically, it is indistinguishable from sebaceous adenitis, and thus there are a group of dermatoses which are probably all different that manifest as mural folliculitis. Clinically mild cases are probably a form of allergic dermatitis^[2]. Thus, lymphocytic mural folliculitis appears to be a pathological reaction pattern rather than a single clinical disease.

It has been described in cats that have one or more well circumscribed annular areas of alopecia that may be total or diffuse. The lesions were seen on the head, limbs and trunk, and scaling and pruritus were variable. Lymphocytic folliculitis in the cat is a reaction pattern and not a disease in itself^[3]. In one case, lymphocytic enteritis associated with the diet was described^[4].

There are many conditions that show this pattern but have different aetiologies. Idiopathic lymphocytic mural folliculitis may be seen in alopecia areata, alopecia mucinosa, early stages of epitheliotropic T cell lymphoma, feline immunodeficiency virus infection, demodicosis, dermatophytosis, pseudopelade, sebaceous adenitis, drug reactions and food intolerance. Rare cases may also be seen in eosinophilic granuloma complex, cryptococcus and sterile pyogranuloma^[5].

The histological patterns can be differentiated to a certain extent by the different parts of the hair follicle or the sebaceous glands that are specifically targeted. To differentiate between these various causes, a complete history, skin scrapings and fungal culture are indicated. In addition, multiple biopsies are important and repeated biopsies may be necessary to document the development of, for example, epitheliotropic T cell lymphoma^[6].

The prognosis is very grave. The condition is invariably fatal for no precise reason. Because the histopathological diagnosis may be associated with various diseases, a specific therapy cannot be recommended. Only a few cases and their variable response to therapy such as oral glucocorticoids or systemic retinoids have been described. Spontaneous remission has been reported^[7].

References

1. ↑ Guaguere, E & Prelaud, P (2000) A practical guide to feline dermatology. Merial, France
2. ↑ Rest, JR (2006) Controversial and emerging diseases. In August, JR (Ed): Consultations in feline internal medicine. Vol 5. Elsevier Saunders, Philadelphia. pp:267-270
3. ↑ Scott DW, Miller WH & Griffin CE (2001) Muller & Kirk's Small Animal Dermatology, 6th edn. WB Saunders, Philadelphia
4. ↑ Declerq, J (2000) A case of diet-related lymphocytic mural folliculitis in a cat. Vet Dermatol 11:75-80
5. ↑ Rosenberg, AS et al (2010) Infiltrative lymphocytic mural folliculitis: a histopathological reaction pattern in skin-biopsy specimens from cats with allergic skin disease. JFMS 12:80-85
6. ↑ Olivry T, Power HT, Woo JC et al. (2000) Anti-isthmus autoimmunity in a novel feline acquired alopecia resembling pseudopelade of humans. Veterinary Dermatology 11:261–270
7. ↑ Willemse T (1997) Psychogenic alopecia in cats and the role of the opioid and dopaminergic systems. In: Consultations in Feline Internal Medicine, vol. 3, ed. JR August, pp. 224–230. WB Saunders, Philadelphia