Clinical, Histologic, and Molecular Analysis of Differences Between Erythematotelangiectatic Rosacea and Telangiectatic Photoaging.

Importance: Facial erythema and telangiectasia are commonly associated with the erythematotelangiectatic subtype of rosacea (ETR). It is important for clinicians to recognize that these findings can also be associated with a subtype of photoaging, which we term telangiectatic photoaging (TP).
Objective: To demonstrate that ETR and TP are distinct dermatologic disorders.
Design: A case-control observational study comparing clinical, histologic, and gene expression features of 26 participants with ETR, 20 with TP, and 11 age- and sex-matched controls in the Program for Clinical Research in Dermatology at University of Michigan.
Main Outcomes and Measures: Findings of clinical history and examination, light and electron microscopy, immunohistochemical analyses, and real-time quantitative reverse-transcriptase polymerase chain reaction gene expression.
Results: Transient erythema was greater in the ETR group (38% graded moderate to severe) than in the TP (0%; P < .001) and control groups (0%; P = .002). Nontransient erythema was also greater in the ETR group (50% graded moderate to severe) than in the TP (25%; P = .03) and control groups (0%; P < .001). Participants with ETR tended to have erythema and telangiectasia primarily on the central face (79%), whereas those with TP tended to have more lateral involvement (57%; P < .001). Those with ETR had significantly less clinical evidence of photodamage (0% graded 6-8 on a photonumeric scale) than those with TP (40% graded 6-8; P = .01). Histologically, there was less evidence of photodamage in ETR than in TP, which had wispy collagen and solar elastosis surrounding blood vessels. Immunohistologic analysis demonstrated greater geometric mean immunostained area by mast cell tryptase staining in ETR samples (0.018%) than in TP (0.004%; P = .01) or control samples (0.001%; P < .001) but no increase in mast cell number, indicative of greater mast cell degranulation. Gene expression of matrix metalloproteinase-3 was 4-fold greater in ETR samples than in TP samples (P = .004) and 5-fold higher than in control samples (P = .004). Gene expression of the neuropeptides calcitonin gene-related peptide (CGRP-α) and substance P was significantly increased in ETR compared with TP (9-fold [P < .001] and 5-fold [P = .002], respectively) and control samples (10-fold [P < .001] and 28-fold [P < .001], respectively).
Conclusions and Relevance: Telangiectatic photoaging is characterized by less transient and nontransient erythema, a more lateral distribution of erythema and telangiectasia, less neurogenic mast cell activation, and less MMP-mediated matrix remodeling than ETR. These data demonstrate that TP is a distinct clinical entity from ETR that can be distinguished on the basis of clinical, histologic, and gene expression findings.