Bilateral malar milia en plaque as primary presentation of discoid lupus erythematosus

Lichen planus follicularis tumidus: Immunotyping of the inflammatory infiltrate with focus on plasmacytoid dendritic cells

Lichen planus follicularis tumidus (LPFT) is a rare clinicopathological variant of lichen planus (LP), clinically presenting with red-to-violaceous plaques studded with comedo-like lesions and keratin-filled milia-like cysts. Histopathologically, LPFT is characterized by cystically dilated follicular infundibula in the dermis, surrounded by a dense lichenoid lymphoid infiltrate with an associated interface reaction. We describe the clinicopathological features of an additional case of LPFT, focusing on the number and distribution of CD123(+) TCF4(+) plasmacytoid dendritic cells (pDCs). In our case, pDCs represented approximately 5% of the total inflammatory infiltrate, predominantly exhibiting a lichenoid distribution around the infundibula with no evidence of cluster formation, thus ruling out cutaneous lupus erythematosus. Our report is the first to describe the number and distribution of pDCs in LPFT. The results of our immunohistochemical analysis corroborate the notion that LPFT should be regarded as a rare variant of LP.

Dermatopathology of Cutaneous Cystic Lesions: A Practical Review With Diagnostic Clues and Pitfalls

BACKGROUND

Cystic lesions are common in the daily practice of dermatologists and dermatopathologists, and in most cases, a straightforward diagnosis can be done. Yet, some variants and situations may cause diagnostic problems or carry prognostic and/or systemic implications.

OBJECTIVE

To review the histopathological features of the most frequent cystic lesions, either true cysts or pseudocysts, and provide some clues and pitfalls to bear in mind for troublesome situations such as solid-cystic tumors; uncommon variants; incidental findings; artifactual, reactive, or infectious cavities; cysts as a warning of systemic and hereditary diseases; and malignant cystic tumors, either primary or metastatic.

METHODS

The histopathological diagnostic criteria of most cystic lesions and their potential caveats will be discussed, offering some diagnostic clues.

RESULTS

Cystic lesions of the skin can primarily be classified into true cysts and pseudocysts. The most frequent pseudocysts are sinus pilonidalis and mucin-filled cavities. True cysts can be divided according to their epithelial origin or differentiation into epidermal/pilar cysts, cysts from glandular appendages, and from embryonic remnants. Diagnostic dilemmas and possible pitfalls in cystic lesions are reviewed, offering some keys to solve them.

CONCLUSIONS

Knowledge of the histopathology of cystic lesions contributes to their correct diagnosis, improving the management of patients.

Lichen planus follicularis tumidus

In this work, the authors described a case of a patient with lichen planus follicularis tumidus (LPFT), an extremely rare variant of lichen planus. The article provides an overview of literature on clinical features characterizing this rare condition. Differential diagnosis as well as treatment of this condition is considered.