Pityriasis lichenoides: Long-term follow-up study

Utility of IL-36 immunostaining in distinguishing psoriasis from pityriasis rosea and pityriasis lichenoides

BACKGROUND

Psoriasis is an inflammatory skin disease driven by upregulation of cytokines in the Th17 pathway, including interleukin-36 (IL-36). Previous studies have highlighted the utility of IL-36 immunostaining for psoriasis compared to spongiotic dermatitis and other psoriasiform dermatoses; however, no study has examined the role of IL-36 staining in distinguishing psoriasis from pityriasis rosea (PR) and pityriasis lichenoides (PL), known histologic mimickers of psoriasis.

METHODS

We compared the immunostaining pattern of IL-36 for 21 PR cases, 22 PL cases, and 10 psoriasis cases. We graded the immunostaining as 0, negative; 1, focal weak; 2, diffuse weak; 3, focal, strong; or 4, diffuse strong. We further categorized stains as negative (0-2 score) or positive (3-4 score) and utilized Fisher's exact test to compare the immunostaining pattern of these entities.

RESULTS

All psoriasis specimens were positive for IL-36, whereas all PR specimens were negative (p = 0.00000002). Twenty PL specimens were negative (p = 0.000001). Nine of 10 pityriasis lichenoides et varioliformis acuta cases were negative (p = 0.00012), and 11 of 12 cases of pityriasis lichenoides chronica were negative (p = 0.00003).

CONCLUSIONS

Our findings highlight the potential role of IL-36 immunostaining in distinguishing psoriasis from other psoriasiform dermatoses, including PR and PL.

Pityriasis lichenoides: assessment of 41 pediatric patients

OBJECTIVES

This study aims to evaluate the characteristics and treatment response of patients with pityriasis lichenoides seen in the last 43 years in a pediatric dermatology service.

METHODS

This was a retrospective, analytical, longitudinal study of patients under 15 years of age. The medical records were reviewed and data were presented as frequencies, means and variances. Student's t-test, Mann-Whitney test, Fisher's exact test, Pearson/Yates chi-square test and multivariate logistic regression model were used, with p < 0.05 considered.

RESULTS

41 patients were included, 32 (78.0%) with pityriasis lichenoides chronica (PLC), five (12.2%) with pityriasis lichenoides et varioliformis acuta (PLEVA) and four (9.8%) with clinical PLC without biopsy. The age range of school children and adolescents was 19 (46.3%) and 13 (31.7%) respectively and 27 (65.8%) were male. Two peaks of the highest frequency were observed between 2004 and 2006 (10 patients - 24.4%) and another between 2019 and 2021 (6 patients - 14.7%). There was remission in 71.9% (n = 23), with 56.6% (n = 17) of those who used antibiotic therapy and 80% (n = 4) of those who had phototherapy. The chance of remission was 13 times greater in patients with disease onset after 5 years of age.

CONCLUSIONS

The clinical form most commonly found was PLC mainly in school children and adolescents. The frequency peaks coincided with infectious outbreaks. The remission rate was satisfactory with antibiotic therapy, but higher with phototherapy. Remission was greater in patients with disease onset after 5 years of age.

Pediatric Cutaneous Hematologic Disorders: Cutaneous Lymphoma and Leukemia Cutis: Experience of a Tertiary-Care Pediatric Institution and Review of the Literature

BACKGROUND

Cutaneous hematologic malignancies are rare in children, and the literature about them is still sparse.

OBJECTIVE

The purpose of our study was to report our experience with pediatric cases of cutaneous hematologic disorders and describe their clinical and histological features.

METHODS

Data were retrospectively collected from the histopathologic database of the CHU Sainte-Justine, University of Montreal, Montreal, Canada. All patients up to 18 years of age with a diagnosis of a primary cutaneous lymphoma (including lymphomatoid papulosis), secondary cutaneous lymphoma or cutaneous manifestations of leukemia, followed from 1980 to 2019 at our center were reviewed.

RESULTS

Thirty-six patients were included. Age at presentation ranged from birth to 18 years of age (mean 7.83 ± 5.16; median 7.0). Ten different hematologic disorders were identified according to the WHO-EORTC classifications: lymphomatoid papulosis (10 cases), mycosis fungoides (6 cases), anaplastic large cell lymphoma (4 cases), pre-B acute lymphoid leukemia (5 cases), primary cutaneous marginal zone B-cell lymphoma (4 cases), primary cutaneous CD4⁺medium T-cell lymphoproliferative disorder (1 case), extranodal NK/T-cell lymphoma (1 case), hydroa vacciniforme-like lymphoproliferative disorder (1 case), B-cell lymphoblastic lymphoma (1 case) and acute myeloid leukemia (3 cases).

CONCLUSION

The most common subtype of cutaneous hematologic disease in our single institution study was lymphomatoid papulosis (type A and type C), followed by mycosis fungoides. Recognition of this large clinical and histological spectrum by dermatologists is important because diagnosis is often established by biopsy of skin lesions, even in secondary cutaneous cases. Moreover, the clinicopathological correlation is of utmost importance for the final diagnosis of those pathologies.

Infectious exanthemas in childhood

Most childhood exanthemas are harmless. However, recognizing serious diseases with life-threatening complications at an early stage is important for the timely initiation of adequate therapy. This requires knowledge of the specific patterns of the exanthema, obtained from the medical history and the clinic, including the patient's general condition and physical examination. In unclear cases, additional diagnostic measures are undertaken, such as blood tests and smears (cutaneous, mucocutaneous). Viruses are the most common cause of childhood exanthemas. New variants of infectious agents, improved diagnostics and stays in tropical and subtropical countries have expanded the spectrum of infectious exanthemas.

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) or febrile ulceronecrotic Mucha-Habermann disease (FUMHD) mixes clinical and chronological features. In this retrospective monocentric study, we aimed to investigate the relevance of the classification in routine practice. We included 49 patients (25 women, median age 41 years). The lesions were papular in 76% of patients, necrotic in 12%, and mixed in 12%. We found three histological patterns: "classical" (65%), "lymphomatoid" (13%), and "mild" (22%). The "lymphomatoid" pattern was associated with necrotic presentation and the "mild' pattern with papular lesions (p=0.012). Among the 27 patients with follow-up, 18% had relapses and 44% a chronic form. One patient had mycosis fungoides. Neither clinical nor histological aspects were correlated with disease progression. Clinical and histological pictures reflect more the intensity of epidermal injury rather than disease course. "Pityriasis lichenoides" should be preferred to the classical PLEVA/PLC classification.

Phototherapy in the Pediatric Population

Phototherapy has been used successfully to treat a wide range of pediatric skin conditions. It is a viable option in children with severe dermatologic disease or who have failed first-line treatments, and several studies have demonstrated its efficacy and safety in the pediatric population. Despite the growing body of evidence on the use of phototherapy in children, large controlled trials and long-term studies are lacking. Moreover, special considerations must be taken when using phototherapy in children. This review highlights the recent evidence supporting the efficacy and safety of phototherapy in children, with focus on the common light-sensitive pediatric skin conditions.