John G. Hancox

Seasonal variation of dermatologic disease in the USA: a study of office visits from 1990 to 1998.

Background  Seasonal variation has been demonstrated in many diseases, including certain skin diseases.

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.

Adult onset folliculocentric langerhans cell histiocytosis confined to the scalp.

Langerhans cell histiocytosis (LCH) is a pleomorphic disease entity characterized by local or disseminated atypical Langerhans cells found most commonly in bone, lungs, mucocutaneous structures, and endocrine organs. Cutaneous disease occurs in approximately one quarter of all cases. Cutaneous findings include soft-tissue swelling, eczematous changes, a seborrheic dermatitis-like appearance, and ulceration. We report a rare case of LCH confined to the scalp with folliculocentric infiltrates. This 32-year-old male patient presented with follicularly based erythema, scale, and pustules unresponsive to topicals and oral antibiotics. The patients lesions mimicked lichen planopilaris and folliculitis decalvans during the disease process. On hematoxylin and eosin stain, scalp biopsy showed a perivascular interstitial patchy lichenoid mononuclear cell infiltrate that focally abutted follicular infundibula. Prominent mononuclear cells having reniform nuclei were present, and immunoperoxidase stains for CD1a confirmed Langerhans cell differentiation. Serological and imaging workup failed to display systemic involvement.