Serration pattern analysis as a practical adjunct tool for categorization of subepidermal autoimmune blistering diseases.

BACKGROUND: Serration pattern analysis helps in the classification of subepidermal autoimmune blistering disorders; more precisely, it helps to differentiate epidermolysis bullosa acquisita from other subepidermal autoimmune blistering disorders. Most of the published reports of this tool have come from a single center. OBJECTIVES: The objectives of the study were to study the utility of serration pattern analysis in classifying subepidermal autoimmune blistering disorders. METHODS: Seventy five cases of subepidermal autoimmune blistering disorders were enrolled in this prospective study. A three millimeter punch biopsy was taken from the perilesional skin or mucosa for direct immunofluorescence; indirect immunofluorescence was carried out using salt-split skin. Subclassification of subepidermal autoimmune blistering disorders was done based on direct immunofluorescence, indirect immunofluorescence on salt-split skin, indirect immunofluorescence using knockout skin and serration pattern analysis findings. RESULTS: Indirect immunofluorescence was positive in 68 cases; 14 cases showed a dermal staining pattern while the rest showed either an epidermal or a combined pattern. All patients with epidermal or combined staining patterns showed "n" serrated pattern on direct immunofluorescence. Nine patients with dermal staining on indirect immunofluorescence also revealed an "n" serration pattern on direct immunofluorescence indicating the diagnosis of anti-p200 pemphigoid, and the rest showed a "u" serrated pattern. Three patients with negative indirect immunofluorescence showed "u" serration on direct immunofluorescence while the rest showed "n" serration. LIMITATIONS: ELISA and immunoblotting could not be performed due to resource constraints. CONCLUSION: Based on indirect immunofluorescence and serration pattern analysis, classification of the majority of patients with subepidermal autoimmune blistering disorders was possible in our study. Pattern recognition is a cost-effective tool and can be easily learnt. It is recommended to be practiced in all laboratories where facilities for advanced immunological diagnosis are unavailable.

A case of pyoderma gangrenosum induced by insulin.

Pyoderma gangrenosum (PG) is a rare auto-inflammatory, neutrophilic, ulcerative disorder characterised by acutely painful, rapidly spreading, sterile ulcers over the trunk and lower limbs. The pathogenic mechansim of PG is under constant evolution and drugs are emerging to be a an important trigger. In the literature, 52 cases of drug-induced PG have been documented, of which cocaine laced with levamisole has shown most direct association, with a mean Naranjo score of 9. Other drugs probably associated with PG are isotretinoin, sunitinib, and propylthiouracil. We describe a case of a 59-year-old male who had multiple well-defined ulcers with a violaceous, undermined edge limited to the site of subcutaneous injection of insulin. Histopathological examination showed psoriasiform hyperplasia in the epidermis, with abundant infiltration of neutrophils in the dermis, consistent with the clinical diagnosis of PG. As per the modified Naranjo algorithm, the patient's total score was 7, indicating insulin to be the probable causative agent in our case. So, compiling temporal localisation of lesions to the site of administration of insulin and clinical, histopathological, and Naranjo score evidence all prompt the diagnosis of PG. Insulin stimulates the release of matrix-metalloproteinases 9 which acts as endopeptidases and also results in the chemotaxis of neutrophils, causing ulcer formation. This is the first case reporting PG triggered by insulin.