Spring and summer eruption of the elbows: a peculiar localized variant of polymorphous light eruption.

Background: Polymorphous light eruption (PLE) is the most common form of idiopathic photodermatosis. Several morphologic variants of PLE have been described, including a localized form of PLE primarily affecting the helices of the ears. To our knowledge, the presence of lesions on the elbows as the unique manifestation of PLE has not yet been reported. We have studied 9 patients presenting with a recurrent eruption on the elbows, with clinical and histopathologic features indistinguishable from PLE, occurring during springtime. Recently, a peculiar eruption of the elbows, with similar clinical features to our patients, has been proposed as a manifestation of cutaneous lupus erythematosus.

Objective: We sought to describe the clinical, histopathological, and immunohistochemical features of this peculiar eruption of the elbows.

Methods: Nine patients presenting a recurrent spring eruption on the elbows, collected from April 1989 to June 2012, were retrospectively analyzed. We studied their clinical and histopathological features, and the immunophenotype of the infiltrate.

Results: Five patients were men and 4 were women. The mean age was 44.7 years. The lesions consisted of pruriginous, erythematous-edematous papules and plaques, located on both elbows. The eruption appeared during the spring or early summer and recurred seasonally. No associated symptoms were present and the eruption regressed spontaneously or with topical corticosteroids after 7 to 15 days. Histopathologically, the lesions showed typical features of PLE, with variable degree of edema in the papillary dermis, and a papillary and reticular dermal perivascular infiltrate mostly composed of small lymphocytes. Immunohistochemical studies demonstrated strong immunoreactivity for CD2, CD4, and CD8, revealing the infiltrate was composed predominantly of T lymphocytes, with a predominance of T-helper over T-cytotoxic lymphocytes. Immunostaining for CD123 was negative, highlighting the absence of plasmacytoid dendritic cells. Other T- and B-cell markers, including CD30, PD-1, CXCL13, FoxP3, CD79a, and CD56 were also negative.

Limitations: Retrospective case series design is a limitation. Phototests were not performed. Results of antinuclear antibodies were only available in 1 patient.

Conclusions: We believe this recurrent eruption of the elbows represents a distinctive and localized variant of PLE rather than a peculiar manifestation of cutaneous lupus erythematosus and suggest the term "spring and summer eruption of the elbows" for this peculiar condition. The mechanism of this localization on the elbows, with sparing of other photoexposed areas, remains unknown.