Pinpoint papular variant of polymorphous light eruption: clinical and pathological correlation.

BACKGROUND: Polymorphous light eruption (PMLE) is the most common chronic idiopathic photodermatosis usually manifesting as a papular eruption along with several other morphological variants including a pinpoint papular variant. METHODS AND MATERIALS: Between June 1998 and August 2003, 10 PMLE patients presented to the Department of Dermatology at Henry Ford Hospital with complaints of a pruritic pinpoint papular eruption associated with sun exposure. In six patients skin biopsies were performed along with a detailed history and complete skin examination. We correlated the histology with the clinical course of disease corresponding to acute and subacute disease presentation. We also performed immunohistochemistry on three cases to study the immunophenotype in PMLE. RESULTS: The clinical, histologic and immunostain findings are summarized. Acute: Clinically pinpoint papules and vesicles, some with erythematous base, were seen. Histology showed focal vesicle formation, spongiosis, oedema, red blood cells extravasation, and superficial and deep perivascular and interstitial lymphocytic infiltrate with occasional eosinophils. Subacute: Clinically pinpoint papules with or without erythema were seen. Histology of the pinpoint lesion showed a nodular collection of lymphocytes and histiocytes with claw-like extension of epidermal rete ridges at the lateral boundaries of the lesion. Overlying epidermal atrophy with adjacent spongiosis, exocytosis, oedema and a superficial perivascular lymphocytic infiltrate and parakeratosis was also observed. The histologic differential diagnosis included lichen nitidus. Immunohistochemical stains revealed the following results: CD8, CD68 positive, CD4 variable (strongly positive to negative) and S-100 negative. CONCLUSION: (i) Pinpoint papular variant of PMLE is a distinct entity, which shows characteristic histology corresponding to the clinical course of the disease (acute and subacute). (ii) The histologic and immunophenotypic differential diagnosis of this variant during the subacute phase includes lichen nitidus.

Analysis of RUNX1 binding site and RAPTOR polymorphisms in psoriasis: no evidence for association despite adequate power and evidence for linkage.

BACKGROUND: A previous study identified two peaks of allelic association between psoriasis and single nucleotide polymorphisms (SNPs) mapping to distal chromosome 17q, including a disease associated SNP that leads to loss of a RUNX1 transcription factor binding site, and additional SNPs in the third intron of the RAPTOR gene. Another study found an association with SNPs in the RAPTOR gene, but not with the RUNX1 binding site polymorphism. METHODS: In an effort to confirm these observations, we genotyped 579 pedigrees containing 1285 affected individuals for three SNPs immediately flanking and including the RUNX1 binding site, and for three SNPs in the RAPTOR gene. RESULTS: Here we report further evidence for linkage to distal chromosome 17q, with a linkage peak mapping 1.7 cM distal to the RUNX1 binding site (logarithm of the odds 2.26 to 2.73, depending upon statistic used). However, we found no evidence for association to individual SNPs or haplotypes in either of the previously identified peaks of association. Power analysis demonstrated 80% power to detect significant association at genotype relative risks of 1.2 (additive and multiplicative models) to 1.5 (dominant and recessive models) for the RUNX1 binding site, and 1.3 to 1.4 for the RAPTOR locus under all models except dominant. CONCLUSIONS: Our data provide no support for the previously identified RUNX1 binding site or for the RAPTOR locus as genetic determinants of psoriasis, despite evidence for linkage of psoriasis to distal chromosome 17q.