Langerhans cell microgranulomas (pseudo‐pautrier abscesses): morphologic diversity, diagnostic implications and pathogenetic mechanisms

Abstract

The term ‘Langerhans cell microgranuloma’ (LCM) was introduced a decade ago to draw attention to focal collections of these cells within the epidermal layer that develops during certain immune reactions. In spite of a growing awareness of this phenomenon during the past decade, few reports have focused on the development and phenotype of LCM. In this commentary, we review the historical development of the concept of LCM, demonstrate the salient immunomorphologic characteristics of LCM, and advance a hypothesis to explain their sequential evolution and formation.

Regulatory T cells in atopic dermatitis: epidermal dendritic cell clusters may contribute to their local expansion

“…LCMs have been described as a focal accumulation of CD1a+ intraepidermal DCs that can develop during certain immune reactions, predominately in spongiotic dermatitis and lichenoid dermatitis. 26,27 The immunophenotype was shown to be CD1a+, S-100+, as well as CD11b+, CD36+, CD68+ and variably CD83+. The epidermal DC aggregates we found in our APT-positive skin samples showed a CD1a+CD11c+CD40+ CD123)CD207) phenotype.…”

“…None of the chronic active AD samples showed epidermal DC aggregates. LCMs have been described as a focal accumulation of CD1a+ intraepidermal DCs that can develop during certain immune reactions, predominately in spongiotic dermatitis and lichenoid dermatitis 26,27 . The immunophenotype was shown to be CD1a+, S‐100+, as well as CD11b+, CD36+, CD68+ and variably CD83+.…”

Pseudomalignancies in Children: Histological Clues, and Pitfalls to Be Avoided

“…This LCH-mimicking phenomenon is often referred to as "Langerhans cell hyperplasia" and can lead to misdiagnosis. Some cases do not display these characteristic morphologic features and are only discovered after immunostaining with anti-CD1a [28,32]. The Langerhans cells are often located in the dermis around the vessels, but can also be encountered in the epidermis-mostly in spongiotic disorders, such as Langerhans cell microgranulomas and pseudo-Pautrier abscesses [32].…”

“…Some cases do not display these characteristic morphologic features and are only discovered after immunostaining with anti-CD1a [28,32]. The Langerhans cells are often located in the dermis around the vessels, but can also be encountered in the epidermis-mostly in spongiotic disorders, such as Langerhans cell microgranulomas and pseudo-Pautrier abscesses [32]. There are a few histological features that facilitate the differential diagnosis between CD1a+ DCH and LCH:…”

Spongiotic dermatitis with Langerhans cell microvesicles

“…2 The development of LCMs has been described in subacute dermatitis, as well as in allergic contact dermatitis. 3 The 68-year-old Caucasian male complaining of a sudden appearance of erythematous papules, plaques and few blisters on the abdomen, back, arms and thighs. Physical examination confirmed these findings.…”