Background <p>Psoriasiform dermatitis can be defined both clinically and histologically, but is not a traditionally recognized clinical or histologic diagnosis.</p> Objective <p>Analyze the final clinical diagnosis, demographics and clinical characteristics in patients with histologic psoriasiform dermatitis.</p> Methods <p>Retrospective cross-sectional analysis of patients with histologic psoriasiform dermatitis 2004–2017.</p> Results <p>Patients (<i>N</i> = 586) were most often female (53.4%) and race/ethnicity included White (61.3%), Black (29.5%), Asian (4.8%), Hispanic (0.7%); mean (SD) age was 52.0 (17.9) years. Median time from histologic psoriasiform dermatitis to final clinical diagnosis was 0.5 months and median duration of follow-up was 6.0 years. The most frequently involved body sites were legs (37.2%), trunk (35.8%) and arms (25.3%). Final clinical diagnoses most associated with histologic psoriasiform dermatitis were psoriasis (<i>N</i> = 191, 32.6%), dermatitis (<i>N</i> = 173, 29.5%), “no clinical diagnosis” (<i>N</i> = 59, 10.1%) and cutaneous T-cell lymphoma (CTCL) or parapsoriasis (<i>N</i> = 48, 8.2%).</p> Limitations <p>Retrospective study at one academic center.</p> Conclusion <p>The most frequent clinical diagnoses associated with histologic psoriasiform dermatitis were psoriasis in about one third of patients, dermatitis in just under one third of patients, “no clinical diagnosis” in approximately 10% and CTCL/parapsoriasis in just under 10%.</p>