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Autoimmunity

It is grouped as follows.

Clinical evidence-Significant association between AA & Hashimoto’s thyroiditis, Addisons, disease and pernicious anaemia has been statistically reported.Other autoimmune diseases occurred with AA include vitiligo, lichen planus, SLE, ulcerative colitis, myasthenia gravis, autoimmune haemolytic anaemia, DM.

 

Humoral immunity- There is an evidence of circulating organ-

Specific antibodies against thyroid, gastric parietal cell, adrenal tissue, smooth muscle, testes and ovaries in patients with AA.

 

Histopathologic evidence- Lymphocytic infiltration around the Follicles in the affected skin is seen.

 

Cell mediated immunity-Study shows that hair bulb keratinocytes Expressed HLA-DR antigen, a phenomenon indicative of immunological cell injury. The response of AA to immunomodulators (eg- contact sensitizers, PUVA, steroids) also support the theory.

 

Association with Down’s syndrome- 60 cases of AA were found in 100 children with Down’s syndrome.

 

AA is a disease of differentiating cortical keratinocytes leading to defective keratinization, shaft fracture & precipitation of telogen.

 

Examination

Well defined , round, oval areas, skin is smooth & soft on any hair bearing areas. No scarring. Exclamation hairs around margins. (Brush like tip 3mm-10mm above scalp surface, less pigmented shaft & atrophic root).

Disturbed keratinization.

 

Transition into telogen.

  • Regrowing hairs- usually vellus
  • Nail changes- Pitting of nails

 

Diagnosis

It is based mainly on clinical presentation & histology. Trichogram reveals a mixed telogen-dystrophic pattern. Miniaturization of follicles seen in later course of disease.

  • Peribulbar lymphocytic infiltrate in a swarm of bees pattern is characteristic of the disease.
  • Eosinophils present in fibrous tracts & in peribulbar location are helpful in long standing AA.

Differential Diagnosis

AA/Telogen Effluvium/Anagen Effluvium- It depends on the elicitation of the initiating cause of the effluvium.

 

Androgenetic Alopecia- Differentiated by age related progressive course, typical distribution & thinning of hair.( There is no complete Alopecia like AA). Trichogram shows raised telogen count without any dystrophic hair & varying thickness of anagen hair.

 

Traumatic Alopecia-It is distinguished by a history or evidence of trauma.


Bacterial Folliculitis, Pyogenic scalp infections, Tinea capitis,  Insect bites-
In these conditions there is an evidence of inflammation.

 

Syphilitic Alopecia- There is rapid onset of closely grouped ,irregular pea-sized patches of incomplete alopecia over the temples/occiput leading to a moth eaten appearance.

 

Metastatic breast carcinoma- AA may be the first sign. Past history of breast cancer, slight erythema & induration of affected skin. Condition can be confirmed by biopsy.

 

 





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