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 are scarce. OBJECTIVES: To characterize the epidemiological, clinical, histopathological and prognostic features of paediatric LyP. METHODS: This was a retrospective multicentre international cohort study that included 87 children and adolescents with LyP diagnosed between 1998 and 2022. Patients aged ≤ 18 years at disease onset were included. LyP diagnosis was made in each centre, based on clinicopathological correlation. RESULTS: Eighty-seven patients from 12 centres were included. Mean age at disease onset was 7.0 years (range 3 months-18 years) with a male to female ratio of 2 : 1. Mean time between the onset of the first cutaneous lesions and diagnosis was 1.3 years (range 0-14). Initial misdiagnosis concerned 26% of patients. LyP was most often misdiagnosed as pityriasis lichenoides et varioliformis acuta, insect bites or mollusca contagiosa. Erythematous papules or papulonodules were the most frequent clinical presentation. Pruritus was specifically mentioned in 21% of patients. The main histological subtype was type A in 55% of cases. When analysed, monoclonal T-cell receptor rearrangement was found in 77% of 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. Associated haematological malignancy (HM) occurred in 10% of cases (n = 7/73), including four patients with mycosis fungoides, one with primary cutaneous anaplastic large cell lymphoma (ALCL), one with systemic ALCL and one with acute myeloid leukaemia. If we compared incidence rates of cancer with the world population aged 0-19 years from 2001 to 2010, we estimated a significantly higher risk of associated malignancy in general, occurring before the age of 19 years (incidence rate ratio 87.49, 95% confidence interval 86.01-88.99). CONCLUSIONS: We report epidemiological data from a large international cohort of children and adolescents with LyP. Overall, the disease prognosis is good, with excellent survival rates for all patients. Owing to an increased risk of associated HM, long-term follow-up should be recommended for patients with LyP.

Lymphomatoid papulosis is a very rare skin condition caused by an abnormal increase in white blood cells (called 'lymphocytes') in the skin. The condition rarely affects children, so most of the scientific data published about this disease focuses on adults. This study involved 12 academic dermatology centres in Europe, the Middle East and North America, and gathered data from about 87 children who presented with symptoms of lymphomatoid papulosis before the age of 19 years. The aim of this study was to better describe this disease in the paediatric population and discuss its treatment options and evolution. We found that the presentation of the disease in children is roughly the same as in adults. Safe and effective treatment options exist. The disease is not life threatening, but it requires investigation by a dermatologist, both to make a careful diagnosis and to monitor it as sometimes associated cancers that originate from blood cells can occur, mostly on the skin.

Treatment of extramammary Paget's disease with imiquimod in a real-life setting: a multicenter retrospective analysis in Spain.

BACKGROUND: Topical imiquimod has shown to be an effective treatment for EMPD, although available evidence supporting its use is based on case reports and small series of patients. OBJECTIVES: To investigate the therapeutic outcomes and analyze potential clinico-pathological factors associated with imiquimod response in a large cohort of EMPD patients. METHODS: Retrospective chart review of 125 EMPD patients treated with imiquimod at 20 Spanish tertiary-care hospitals. RESULTS: During the study period, patients received 134 treatment regimens with imiquimod, with 70 (52.2%) cases achieving complete response (CR), 41 (30.6%) partial response and 23 (17.2%) no response. The cumulative CR rates at 24 and 48 weeks of treatment were 46.3% and 71.8%, respectively, without significant differences between first-time and previously treated EMPD. Larger lesions (≥6 cm; p = 0.038) and EMPD affecting >1 anatomical site (p = 0.002) were significantly associated with a worse treatment response. However, the CR rate did not differ significantly by the number of treatment applications (≤4 vs. > 4 times/week; p = 0.112). Among patients who achieved CR, 30 (42.9%) developed local recurrences during a mean follow-up period of 36 months, with an estimated 3 and 5-year recurrence free-survival of 55.7% and 36.4%, respectively. CONCLUSIONS: Imiquimod appears as an effective therapeutic alternative for both first-line and previously treated EMPD lesions. However, a less favorable therapeutic response could be expected in larger lesions and those affecting >1 anatomical site. Based on our results, a 3-4 times weekly regimen of imiquimod with a treatment duration of at least 6 months could be considered an appropriate therapeutic strategy for EMPD patients.

Combined Merkel Cell Carcinoma and Squamous Cell Carcinoma: A Systematic Review.

Combined Merkel cell carcinoma (MCC) and squamous cell carcinoma (SCC) have classically been regarded as more aggressive than conventional, pure, Merkel cell polyomavirus (MCPyV)-positive MCC. It is still unknown whether combined MCC and SCC are more aggressive than pure, MCPyV-negative MCC, and the origin of both the SCC and MCC elements of these combined tumors has not been elucidated. The main objective of this systematic review was to assess whether combined MCC and SCC tumors are associated with a worse prognosis than pure MCC; the secondary goals were the characterization of the clinical and histopathological features of these combined neoplasms. A total of 38 studies, including 152 patients, were selected for review. In total, 76% of the cases were MCPyV-negative, whereas 4% were MCPyV-positive. The most frequent histopathological pattern was that of an SCC in situ combined with a dermal MCC (36%), followed by both an in situ and invasive SCC combined with a dermal MCC (20%). Forty-seven percent of all cases fitted in the morphology of the so-called "collision tumors". Three combined MCC cases that would fit in the morphological category of collision tumors presented both squamous and neuroendocrine elements in their respective nodal metastases. The mean overall survival was 36 months, comparable to that of pure, MCPyV-negative MCC. This review found similarly aggressive behavior for combined MCC and SCC and pure, MCPyV-negative MCC. Preliminary data strongly suggest that all MCPyV-negative MCC tumors, whether combined or pure, are part of a common spectrum.

Therapeutic outcomes and survival analysis of Extramammary Paget's disease: A multicentre retrospective study of 249 patients.

BACKGROUND: Evidence regarding long-term therapeutic outcomes and disease-specific survival (DSS) in Extramammary Paget's disease (EMPD) is limited. OBJECTIVES: To assess the DSS and outcomes of surgical and nonsurgical therapeutic modalities in a large cohort of EMPD patients. METHODS: Retrospective chart review of EMPD patients from 20 Spanish tertiary care hospitals. RESULTS: Data on 249 patients with a median follow-up of 60 months were analyzed. The estimated 5-, 10-, and 15-year DSS was 95.9%, 92.9%, and 88.5%, respectively. A significantly lower DSS was observed in patients showing deep dermal invasion (≥1 mm) or metastatic disease (P < .05). A ≥50% reduction in EMPD lesion size was achieved in 100% and 75.3% of patients treated with surgery and topical therapies, respectively. Tumor-free resection margins were obtained in 42.4% of the patients after wide local excision (WLE). The 5-year recurrence-free survival after Mohs micrographic surgery (MMS), WLE with tumor-free margins, WLE with positive margins, radiotherapy, and topical treatments was 63.0%, 51.4%, 20.4%, 30.1%, and 20.8%, respectively. LIMITATIONS: Retrospective design. CONCLUSIONS: EMPD is usually a chronic condition with favorable prognosis. MMS represents the therapeutic alternative with the greatest efficacy for the disease. Recurrence rates in patients with positive margins after WLE are similar to the ones observed in patients treated with topical agents.

Topical Imiquimod in Primary Cutaneous Extramammary Paget's Disease: A Systematic Review.

Extramammary Paget's disease (EMPD) is subclinical in extent and multifocal in nature. There is no global consensus for treatment, so its management represents a challenge in clinical practice. Therefore, we conducted a systematic review through the main electronic databases to assess the effectiveness of topical imiquimod in cutaneous EMPD and to discuss its management. Finally, 24 studies involving a total of 233 EMPD patients treated with topical imiquimod were selected. The topical imiquimod response rate was 67%, and the complete response (CR) rate was 48%. Patients were treated with a three-four times a week regimen in most cases, ranging between 2 to 52 weeks. In addition, imiquimod was applied as an adjunctive treatment in 21 patients, achieving a CR rate of 71%. Consequently, imiquimod therapy could achieve a good response ratio as a first-line treatment, as adjuvant and neo-adjuvant therapy, and as a treatment for recurrent disease. The heterogeneity between studies and the lack of a control arm made it impossible to conduct a meta-analysis. To improve the quality of evidence on EMPD, multicenter studies are essential to collect a larger number of patients and, consequently, obtain high-quality evidence to standardize treatment. The Prospero registration number is CRD42023447443.

Trichoepithelioma on the Finger: A Rare Location and Dermoscopic-Histopathologic Correlation.

ABSTRACT: Trichoepithelioma is a benign adnexal neoplasm of follicular germinative cells, with bulbs, papillae, and sheaths of perifollicular connective tissue as signs of follicular differentiation. Accordingly, trichoepithelioma may arise in any hair-bearing location, mostly on the face. That is why trichoepithelioma cannot appear in glabrous skin, and, although the dorsum of the hands and feet are a hair-bearing area, acral location is exceptional. We report the first case of trichoepithelioma localized in the finger of a 79-year-old man. It was a brown-pink, firm, 7-mm diameter, solid papule on the dorsal aspect of his left index finger. The lesion was completely asymptomatic, and he remembered to have it for many years. We describe this case highlighting its rare anatomical location and correlate its dermoscopic features with the histopathological appearance.