Abstract: A case of granular parakeratosis is reported. A 31-year-old woman presented with a 23-year history of pruritic erythema and erosion in the left axilla. On examination, there was a ring-like annular erythematous patch sized 8 cm × 10 cm in the left axilla. Bright mauve, cone-shaped, millet-like papules were observed in the center of the lesion, some confluenced into plaques. Erythema was present in the perilesional region along with mild erosion, exudation and small numbers of grain-sized pustules. Scar formed in some perilesional areas. No lesions were noted at any other intertriginous regions. Fungal microscopy of lesion secretions was negative. Histological examination of biopsy specimens from the center of the left axilla revealed psoriasiform hyperplasia of epidermis and thickened stratum corneum with hyperkeratosis and parakeratosis. Most cells in the stratum corneum retained nuclei and contained numerous basophilic granules. Granular layer could be noted under the parakeratotic cells with cytoplasm vacuolization of some cells. There was a perivascular, mixed inflammatory infiltration predominated by lymphocytes and hemangiectasis in the dermis. A diagnosis of granular parakeratosis was made.

Key words: parakeratosis, hyalin, pathology