An enlarging ulcerative nodule

A healthy 9-year-old girl, with no past medical history, presented with a 10-day history of a rapidly enlarging, ulcerated 2-cm nodule on her left temple (Figure 1). On further physical examination, a 5-mm papule on her right thigh (Figure 2), scattered millimeter-sized pink papules, and an atrophic scar on her left thigh were noted. Mucosae were spared, and no enlarged lymph nodes nor hepatosplenomegaly were palpated. The review of systems was negative. Punch biopsies for histopathology (Figures 3 and 4) and microbiological analyses were performed on the temple and thigh lesions. The left temple biopsy was non-diagnostic, showing ulceration with an underlying mixed inflammatory infiltrate. Histopathology of the thigh papule revealed a wedge-shaped, dense infiltrate (Figure 3; hematoxylin and eosin; low magnification) containing many large atypical CD30-positive T cells [arrows in Figure 4 (hematoxylin and eosin; high magnification); immunohistochemistry in Figure 5, (CD30 stain)], without epidermotropism, accompanied by mitotic figures and mixed inflammatory cells, including neutrophils, eosinophils and small reactive lymphocytes. Microorganism stains and cultures for bacteria, mycobacteria, leishmaniasis, and deep mycoses were negative. The history of scarring after involution of a previous lesion, the negative cultures, and the classic CD30+ infiltrate confirmed the diagnosis of lymphomatoid papulosis (LyP). LyP is a CD30+ cutaneous T-cell lymphoproliferative disorder (LPD) characterized by recurrent, self-healing crops of asymptomatic erythematous papulo-nodules.1-3 Larger LyP lesions may be ulcerated or necrotic and can lead to varioliform or cribriform disfiguring scars.1, 2, 4 LyP predominantly affects the limbs and trunk, but can involve all sites, including mucosae.4 Eruptions of LyP lesions typically regress after 2–8 weeks, and patients classically have recurrent crops over months to years before resolution of the disease.2 The mean age at lesion onset is 8.5 ± 5 years (standard deviation), with a male-to-female ratio of 1.4:1.4, 5 LyP has an excellent prognosis with no impact on survival, but can be associated with the occurrence of other LPDs.1, 3, 4 In a systematic review of pediatric patients with LyP, 5.6% had a second LPD diagnosed concurrently or during follow-up, sometimes years after the LyP diagnosis.4 The most common associated LPDs are nodal or primary cutaneous anaplastic large cell lymphoma and rarely mycosis fungoides.2, 4-7 Long-term clinical follow-up, at least once a year, is therefore indicated for LyP patients. In children, LyP must be distinguished from arthropod bites, scabietic nodules, pityriasis lichenoides chronica, pityriasis lichenoides chronica et varioliformis acuta, other LPDs and pseudolymphomas. LyP is classified into histopathological subtypes A to F, based on CD30+ lymphocyte morphology and distribution, accompanying inflammatory infiltrate, and immunohistochemistry.8, 9 Type A LyP shows a wedge-shaped infiltrate of large atypical CD30+ lymphocytes intermingled with mixed inflammatory cells.4, 9 At diagnosis, it is important to exclude other systemic LPDs with a complete blood cell count, serum chemistry, and lactate dehydrogenase level. Positron emission tomography-computed tomography (PET-CT) should be reserved for children with systemic symptoms or enlarged lymph nodes.9 The outcome of LyP has not been associated with the duration of the disease, histopathological subtype, number of CD30+ cells, nor the presence of T-cell clones in the biopsy specimens.2, 9, 10 Management with watchful waiting is appropriate for asymptomatic disease, as there is no evidence to suggest that treatment hastens disease remission.3, 4 Potent topical or intralesional corticosteroids can accelerate resolution of individual lesions.3, 4 Other topical therapies with limited evidence, include calcineurin inhibitors, nitrogen mustard, carmustine, imiquimod, and bexarotene.3, 8, 9 For large and persistent lesions, surgical excision or radiation therapy can be locally effective, but should be carefully weighed in the pediatric population.3, 4, 6, 9 To control the occurrence of new crops in extensive or disfiguring LyP, some authors consider low-dose methotrexate (MTX) as being the most effective, with doses ranging between 0.3 and 0.5 mg/kg/week.3, 4 Narrowband ultraviolet B radiation (Nb-UVB) phototherapy has been used successfully with long relapse-free intervals.4, 10 Systemic therapies that have been used in adults include brentuximab-vedotin (anti-CD30), retinoids and interferon-alpha.8, 9 Systemic corticosteroids may be used to reduce existing lesions and can lead to partial remission, but there is limited evidence supporting their use.4 Multi-agent chemotherapy regimens are not recommended as patients experience rapid disease relapse and treatment-related toxicities.3, 6 The necessity of treatment should be frequently reassessed to balance the risk of side effects in an ultimately self-resolving disease, with the risk of scarring. For our patient, clobetasol propionate 0.05% cream was used first, with additional intralesional triamcinolone (10 mg/mL) for larger nodules, with limited success. Because our patient's lesions threatened to cause disfiguring scars, we added prednisone at 1 mg/kg/day tapered over 3 weeks, which led to existing lesion regression. Rapid occurrence of new crops of large nodules with potential to scar led us to start MTX at 0.4 mg/kg/week with poor improvement after 4 months of therapy. Despite normal blood work-up, the poor response to MTX and the large size of the nodules led us to rule-out a more aggressive LPD with a PET-CT scan, which was normal. We elected to switch to isotretinoin 0.3 mg/kg/day combined with Nb-UVB phototherapy. Active follow-up is ongoing. Pediatric LyP poses diagnostic and therapeutic challenges. Therefore, careful clinico-pathological correlation and exclusion of systemic disease are required. Treatment decisions should balance the risk of disfigurement with potential treatment side effects. Continued clinical monitoring is essential to detect other LPDs. We thank the family for accepting to share their story. We have no conflict of interest to declare.

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