Paediatric onset lymphomatoid papulosis: results of a multicentre retrospective cohort study, on behalf of the EORTC Cutaneous Lymphoma Tumours Group (CLTG).

BACKGROUND: Lymphomatoid Papulosis (LyP) is a rare cutaneous T-cell lymphoproliferative disorder. Comprehensive data on LyP in the paediatric population is scarce. OBJECTIVES: To characterize epidemiological, clinical, histopathological, and prognostic features of paediatric LyP. METHODS: This was a retrospective, multicentre international cohort study including 87 cases of children and adolescents with LyP diagnosed between 1998 and 2022. Patients aged ≤ 18 years old at disease onset were included. Diagnosis was made in each centre based on clinical-pathological correlation. RESULTS: Eighty-seven patients from 12 centres were included. The mean age at onset was 7.0 years (range 3 months-18 years) with a male to female ratio of 2:1. The mean time between onset of first cutaneous lesions and diagnosis was 1.3 years (range 0-14 years). Initial misdiagnosis concerned 26.4% of patients. Initially, LyP was most often misdiagnosed as Pityriasis lichenoides et varioliformis acuta (PLEVA), insect bites, or mollusca contagiosa. Erythematous papules or papulonodules were the most frequent clinical presentation. Pruritus was specifically mentioned for 20.7% of patients. The main histological subtype was type A in 55.1% of the cases. If analysed, monoclonal TCR rearrangement was found in 76.5% of the skin biopsies. The overall survival rate was 100% with follow up at 5 years available for 33 patients and at 15 years for 8 patients. A development of associated haematological malignancy (HM) occurred in 9.6% of the cases (7/73), including four mycosis fungoides (MF) cases, one primary cutaneous anaplastic large cell lymphoma (pc-ALCL), one systemic ALCL and one case of acute myeloid leukaemia. If we compare incidence rates of cancer with the world 0-19 years old population from 2001-2010, we estimate a significantly higher risk of associated malignancy in general, occurring before the age of 19 years old with incidence rate ratio of 87.49 (CI 86.01-88.99). CONCLUSIONS: We report epidemiological data from a large international cohort of children and adolescents with LyP. Overall the prognosis of the disease is good, with excellent survival rates for all patients. Due to increased risk of associated HM, a long-term follow-up should be recommended for LyP patients.

Whole-genome profiling of primary cutaneous anaplastic large cell lymphoma.

Primary cutaneous anaplastic large cell lymphoma (pcALCL), a hematological neoplasm caused by skin-homing CD30+ malignant T cells, is part of the spectrum of primary cutaneous CD30+ lymphoproliferative disorders. To date, only a small number of molecular alterations have been described in pcALCL and, so far, no clear unifying theme that could explain the pathogenetic origin of the disease has emerged among patients. In order to clarify the pathogenetic basis of pcALCL, we performed high-resolution genetic profiling (genome/transcriptome) of this lymphoma (n=12) by using whole-genome sequencing, whole-exome sequencing and RNA sequencing. Our study, which uncovered novel genomic rearrangements, copy number alterations and small-scale mutations underlying this malignancy, revealed that the cell cycle, T-cell physiology regulation, transcription and signaling via the PI-3-K, MAPK and G-protein pathways are cellular processes commonly impacted by molecular alterations in patients with pcALCL. Recurrent events affecting cancer-associated genes included deletion of PRDM1 and TNFRSF14, gain of EZH2 and TNFRSF8, small-scale mutations in LRP1B, PDPK1 and PIK3R1 and rearrangements involving GPS2, LINC-PINT and TNK1. Consistent with the genomic data, transcriptome analysis uncovered upregulation of signal transduction routes associated with the PI-3-K, MAPK and G-protein pathways (e.g., ERK, phospholipase C, AKT). Our molecular findings suggest that inhibition of proliferation-promoting pathways altered in pcALCL (particularly PI-3-K/AKT signaling) should be explored as potential alternative therapy for patients with this lymphoma, especially, for cases that do not respond to first-line skin-directed therapies or with extracutaneous disease.

Clinical, Histologic, and Molecular Characteristics of Anaplastic Lymphoma Kinase-positive Primary Cutaneous Anaplastic Large Cell Lymphoma.

Unlike systemic anaplastic large cell lymphoma, the vast majority of primary cutaneous anaplastic large cell lymphomas (C-ALCL) do not carry translocations involving the ALK gene and do not express ALK. Expression of ALK protein therefore strongly suggests secondary cutaneous involvement of a systemic anaplastic large cell lymphoma. Recent studies described a small subgroup of ALK-positive C-ALCL, but information on frequency, prognosis, and translocation partners is virtually lacking. A total of 6/309 (2%) C-ALCL patients included in the Dutch registry for cutaneous lymphomas between 1993 and 2019 showed immunohistochemical ALK expression. Clinical and histopathologic characteristics, immunophenotype and disease course were evaluated. Underlying ALK translocations were analyzed with anchored multiplex polymerase chain reaction-based targeted next-generation sequencing. Median age at diagnosis was 39 years (range: 16 to 53 y). All patients presented with a solitary lesion. Treatment with radiotherapy (n=5) or anthracycline-based chemotherapy (n=1) resulted in complete responses in all 6 patients. Three patients developed a relapse, of whom 2 extracutaneous. After a median follow-up of 41 months, 5 patients were alive without disease and 1 patient died of lymphoma. Immunohistochemically, 3 cases (50%) showed combined nuclear and cytoplasmic ALK expression with underlying NPM1-ALK fusions, while 3 cases (50%) showed solely cytoplasmic ALK expression with variant ALK fusion partners (TRAF1, ATIC, TPM3). ALK-positive C-ALCL is extremely uncommon, has a comparable favorable prognosis to ALK-negative C-ALCL, and should be treated in the same way with radiotherapy as first-line treatment.

Generalized Molluscum Contagiosum Successfully Treated with Interferon-Alpha in a Patient with Folliculotropic Mycosis Fungoides.

We present the case of a 50-year-old patient with folliculotropic mycosis fungoides (FMF) unresponsive to retinoids and the chemotherapeutic regimens CHOP, gemcitabine, and brentuximab-vedotin. During immunosuppressive therapy, the patient developed extensive progressive molluscum contagiosum. The mollusca did not respond to topical imiquimod but showed a swift complete response to interferon-alpha 2a (IFNa). Recently, the patient started with alemtuzumab as induction therapy for an allogenic stem cell transplantation and simultaneously continued IFNa therapy.

Recommendations for the Optimal Radiation Dose in Patients With Primary Cutaneous Anaplastic Large Cell Lymphoma: A Report of the Dutch Cutaneous Lymphoma Group.

PURPOSE: To determine the optimal radiation dose for treatment of primary cutaneous anaplastic large cell lymphoma (C-ALCL) with solitary or localized, multifocal or recurrent skin lesions. METHODS AND MATERIALS: In this multicenter study, patients with C-ALCL who had been treated with radiation therapy (RT) between 1984 and 2016 were retrieved from the Dutch registry of cutaneous lymphomas. Distinction was made between patients first presenting with solitary or localized lesions (n=63), with multifocal skin lesions (n=6), and patients with a skin relapse (n=22). Radiation doses, treatment response, and follow-up were evaluated. Radiation doses were categorized as low-dose (≤20 Gy), intermediate-dose (21-39 Gy), and high-dose (≥40 Gy) RT. RESULTS: Of 63 patients presenting with solitary or localized skin lesions, 61 (97%) showed a complete response (CR). There were no differences in CR between low-dose (16 of 17), intermediate-dose (15 of 15), and high-dose RT (30 of 31). After a median follow-up of 46 months, 30 of 63 patients (48%) had a relapse, but in-field relapses were never observed. Six of 6 patients (100%) initially presenting with multifocal skin lesions showed a CR (3 of 3 low-dose, 2 of 2 intermediate-dose, 1 of 1 high-dose RT). After a median follow-up of 27 months, 3 of 6 patients had a relapse. Treatment of 33 skin relapses in 22 patients showed no differences in CR between low-dose (18 of 19), intermediate-dose (6 of 6), and high-dose RT (8 of 8). In the last 10 years there has been a decrease in radiation dose used in the treatment of C-ALCL. Treatment of multifocal and recurrent lesions with a dose of 8 Gy (2 × 4 Gy) resulted in CR of 17 of 18 lesions. CONCLUSIONS: Our results show that a radiation dose of 20 Gy (8 × 2.5 Gy) is effective in patients presenting with solitary or localized skin lesions. For patients with multifocal skin lesions and patients with a skin relapse, a dose of 8 Gy (2 × 4 Gy) may be sufficient.