Pityriasis lichenoides: a clinical and pathological case series of 49 patients with an emphasis on follow-up.

The classification of pityriasis lichenoides (PL) into pityriasis lichenoides et varioliformis acuta (PLEVA), PL chronica (PLC) and febrile ulceronecrotic Mucha-Habermann disease (FUMHD) is based on both clinical and chronological features. In this retrospective monocentric study, we aimed to investigate the relevance of the classification in routine practice. We enrolled 49 patients (25 female, 24 male; median age 41 years). The lesions were papular in 76% of patients, necrotic in 12% and mixed in 12%. We found three histological patterns: 'classic' (65%), 'lymphomatoid' (13%) and 'mild' (22%). The 'lymphomatoid' pattern was associated with necrotic presentation and the 'mild' pattern with papular lesions (P = 0.01). Among the 27 patients with follow-up, 18% had relapses and 44% had chronic disease. One patient had mycosis fungoides. Neither clinical nor histological findings were correlated with disease progression, and are a reflection of the intensity of epidermal injury rather than of the disease course. The term 'pityriasis lichenoides' should be preferred to the classic PLEVA/PLC/FUMHD classification.

Presentación atípica de pitiriasis liquenoide aguda, reporte de un caso / Atypic presentation of pityriasis lichenoides et varioliformis acuta, a case report

Las pitiriasis liquenoides (PL) son dermatosis polimórficas adquiridas poco comunes que plantean diversos retos, ya que son entidades difíciles de diagnosticar, categorizar y tratar. La pitiriasis liquenoide varioliforme aguda (PLEVA), la pitiriasis liquenoide crónica (PLC) y la enfermedad febril ulceronecrótica de Mucha-Habermann (FUMHD) no son patologías diferentes, por el contrario se consideran manifestaciones diversas dentro de un mismo espectro. Desde el punto de vista histológico son consideradas dermatitis de interfase con infiltrado prominente de linfocitos. La ambigüedad más crítica dentro de este grupo de patologías es la etiología, ya que múltiples agentes han sido implicados sin lograr revelar el mecanismo patológico de esta condición. No existe una modalidad definida de tratamiento; se cree que la terapia combinada es el mejor abordaje para esta patología. Reportamos un caso de un paciente con pitiriasis liquenoide aguda cuya presentación inicial fue atípica lo que nos lleva a considerar diagnósticos como pitiriasis rosada o secundarismo luético.

Pityriasis lichenoides: pathophysiology, classification, and treatment.

Pityriasis lichenoides (PL) is an uncommon, acquired spectrum of skin conditions that poses various challenges to patients as well as clinicians. It is a difficult and debatable disorder to diagnose, categorize, and treat. Besides these inherent obstacles, PL merits awareness because of its potential to progress to cutaneous lymphoma or an ulceronecrotic presentation, both of which carry a significant risk of mortality. The scope of PL presentations is delineated along a continuum of multiple variants including pityriasis lichenoides et varioliformis acuta (PLEVA), pityriasis lichenoides chronica (PLC), and febrile ulceronecrotic Mucha-Habermann disease (FUMHD). Classification of these presentations as separate subsets is debatable in view of their overlapping clinical, histopathologic, and etiologic features. PLEVA generally presents as an acute-to-subacute skin eruption of multiple, small, red papules that develops into polymorphic lesions and vacillates with periods of varying remissions as well as possible sequelae of hyper/hypopigmentation and varicella-like scars. PLC has a more gradual manifestation of very small red-to-brown flat maculopapules with mica-like scale; it also follows a relapsing course but with long periods of remission. FUMHD is an acute and severe generalized eruption of purpuric and ulceronecrotic plaques with associated systemic involvement and a mortality rate of up to 25%; hence, it should be approached as a dermatologic emergency.Histopathological evaluation of PL usually reveals dermal, wedge-shaped, lymphocytic infiltrate, epidermal spongiosis, parakeratosis, and variable necrosis of keratinocytes. PLC demonstrates more subtle histology whereas, at the other end of the spectrum, febrile ulceronecrotic FUMHD exhibits the most exaggerated histological features. The pathogenic mechanism behind PL is unclear although infectious or drug-related hypersensitivity reactions versus premycotic lymphoproliferative disorder are the mainstay theories. The foremost therapies for PLEVA and PLC are phototherapy, systemic antibacterials, and topical corticosteroids. Aggressive treatment with immunosuppressant and/or immunomodulating agents as well as intensive supportive care are recommended for FUMHD. We first describe a representative case of a 14-year-old boy with PLC who was successfully treated with narrow-band UVB. We then review the pathophysiology, classification, and treatment of PL.

Pityriasis lichenoides chronica: stratification by molecular and phenotypic profile.

Pityriasis lichenoides (PL) has traditionally been classified as a benign papulosquamous disease. However, there is an increasing literature precedent that suggests that PL should instead be considered a form of cutaneous lymphoid dyscrasia. We prospectively encountered 46 patients with a diagnosis of PL and used immunohistochemical and multiplex polymerase chain reaction fragment size analysis to assess for phenotypic abnormalities and for T-cell clonal restriction, respectively. We categorized them into 2 groups based on the molecular profile, namely, those cases that showed a monoclonal and/or a restricted oligoclonal profile versus those cases that were polyclonal. Half of all the cases studied showed a monoclonal and/or an oligoclonal restricted T-cell repertoire. From a clinical perspective, 2 cases in this group manifested skin lesions compatible with mycosis fungoides (MF). All of the other cases demonstrated a persistent but nonprogressive clinical course characterized by periods of regression and recurrence. In any case in which there were multiple biopsies, the same T-cell dominant clonotypes, be it in the context of representing a true monoclonal and/or oligoclonal pattern, were implicated over time and at different biopsy sites, including 2 cases in which there was a subsequent evolution to MF. Substantial losses of CD7 and CD62L were seen in both monoclonal/oligoclonal and polyclonal cases of PL, although both values of percentage reduction were greater in the monoclonal/oligoclonal cases. A dominance of CD8 lymphocytes was seen in more than half of all the cases of PL and held to be reactive in nature, potentially directed against clonally restricted CD4 cells. CD4/CD25+ (Foxp3+) T cells averaged 24% in the polyclonal cases; it was 12% in the monoclonal variants of PL. We conclude that PL is a form of indolent cutaneous T-cell dyscrasia. The limited propensity for progression to MF may reflect internal countercheck mechanisms of controlling clonally restricted CD4+ T-cell proliferations via CD8 and CD4/CD25+ regulatory T cells.

Pityriasis lichenoides and its subtypes.

Pityriasis lichenoides represents a unique group of inflammatory skin disorders that include pityriasis lichenoides et varioliformis acuta (PLEVA), febrile ulceronecrotic Mucha-Habermann disease (a subtype of PLEVA), and pityriasis lichenoides chronica. The history, epidemiology, clinical features, pathophysiology, and treatment of this group of conditions are reviewed in this manuscript.