Granular parakeratosis: a case report and literature review.
BACKGROUND
Granular parakeratosis is suspected to result from an error in epidermal differentiation, leading to variably pruritic, hyperpigmented-to-erythematous patches and plaques. Characteristic histopathologic features include a thickened stratum corneum, compact parakeratosis with retention of keratohyalin granules, vascular proliferation, and ectasia. The pathogenesis of this entity is uncertain.


METHODS
We present a case of axillary granular parakeratosis and review the literature.


RESULTS
The lesion showed a thickened stratum corneum with compact parakeratosis, slight epidermal hyperplasia, and a sparse perivascular lymphohistiocytic infiltrate. Keratohyalin granules were diffusely present within the parakeratotic stratum corneum, and the retained granular layer showed focal vacuolization.


CONCLUSIONS
Granular parakeratosis is a rare form of parakeratosis most often seen in the axilla, although other intertriginous areas may be affected. Unique histopathologic findings allow for a specific diagnosis to be made. Although an irritant contact reaction appears causative, mechanical irritation may also play a role in inducing these skin changes.
Wallace
Christopher A
CA
Department of Dermatology, Wake Forest University Baptist Medical Center, Winston-Salem, NC, USA.
Pichardo
Rita O
RO
Yosipovitch
Gil
G
Hancox
John
J
Sangueza
Omar P
OP
D000287:Administration, Topical; D000368:Aged; D001365:Axilla / Q000473:pathology; D005260:Female; D006801:Humans; D010241:Parakeratosis / Q000188:drug therapy / Q000209:etiology / Q000473:pathology*; D014221:Triamcinolone / Q000008:administration & dosage / Q000627:therapeutic use
D014221:Triamcinolone