Panniculitis in Children

Paediatric cutaneous lymphomas including rare subtypes: A 40-year experience at a tertiary referral centre

BACKGROUND

Primary cutaneous lymphomas are neoplasms of the immune system with a distinct tropism for the skin and an absence of extracutaneous manifestations at the time of diagnosis. Studies focusing on cutaneous lymphomas in children and adolescents remain scarce and often do not encompass the rare subtypes.

OBJECTIVES

To address this knowledge gap by describing the clinical, histological and molecular characteristics of a large group of paediatric patients affected by primary cutaneous lymphoma. We also provided the Paediatric Primary Cutaneous Lymphoma Atlas that illustrates the clinicopathological spectrum of observed presentations, in the hope of supporting other physicians in the diagnostic process.

METHODS

Retrospective chart review of paediatric patients diagnosed with primary cutaneous lymphomas between 1980 and 2022 at the Paediatric Dermatology Unit of Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan.

RESULTS

A total of 101 patients (58 males, 43 females) met the inclusion criteria. The most common subtypes were lymphomatoid papulosis (n = 48) and mycosis fungoides (n = 31). These were followed by primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorders (n = 7), primary cutaneous anaplastic large-cell lymphomas (n = 5), primary cutaneous marginal zone B-cell lymphomas (n = 3), primary cutaneous follicle centre lymphomas (n = 2), subcutaneous panniculitis-like T-cell lymphomas (n = 2), primary cutaneous peripheral T-cell lymphoma not otherwise specified (n = 1), primary cutaneous precursor B-lymphoblastic lymphoma (n = 1) and Sézary syndrome (n = 1). Clinical follow-up data covering a median of 70.8 months (range 1-324) were available for 74 patients, of whom three died due to cutaneous lymphoma.

CONCLUSIONS

Our findings shed light on the peculiar aspects and long-term outcomes of paediatric cutaneous lymphomas, particularly emphasizing their distinctive features in comparison to their adult counterparts and exploring the less common subtypes. Further larger-scale studies are warranted to better characterize these entities and to achieve a more rapid and accurate diagnosis.

Imaging features for the evaluation of skin and nail infections

Clinical manifestations of dermatological and musculoskeletal conditions can sometimes overlap, leading to confusion in diagnosis. Patients with nail and skin infections may undergo imaging examinations with suspicions of muscle, tendon, or joint injuries. Dermatological infections often involve soft tissues and musculoskeletal structures, and their etiology can range from fungi, bacteria, viruses, to protozoa. Relying solely on physical examination may not be sufficient for accurate diagnosis and treatment planning, necessitating the use of complementary imaging exams. The objective of this paper is to present and discuss imaging findings of the main infectious conditions affecting the nail apparatus and skin. The paper also highlights the importance of imaging in clarifying diagnostic uncertainties and guiding appropriate treatment for dermatological conditions.

Early-onset recurrent panniculitis as a phenotype of NLRC4-associated autoinflammatory syndrome: Characterization of pathogenicity of the p.Ser445Pro NLRC4 variant

Monoallelic NLRC4 gain-of-function variants cause an inflammasomopathy with diverse clinical forms including infantile enterocolitis, recurrent macrophage activation syndrome, cold-induced urticaria-like lesions (or familial-cold autoinflammatory syndrome, FCAS4), and painful subcutaneous nodules. Here, we identified a large family with six consecutive generations affected. Genetic analyses detected the heterozygous p.Ser445Pro NLRC4 variant in three patients, which has been previously reported in a Dutch family with FCAS4. We aimed to describe the clinicopathological features and the functional consequences of the detected NLRC4 variant. Patients presented an early-onset (3 months-6 years) inflammatory disease characterized by recurrent panniculitis, fever and arthralgia. Histopathological examination showed perivascular and interstitial lymphohistiocytic infiltrates in the dermis and mixed panniculitis. Functional analysis supported the conclusion that the p.Ser445Pro NLRC4 variant leads to a constitutive activation of NLRC4-inflammasome and increased plasma levels of IL-18. Prompt recognition of early-onset panniculitis through clinicopathological examination and laboratory biomarkers may allow targeted therapies.

NEMO-NDAS: A Panniculitis in the Young Representing an Autoinflammatory Disorder in Disguise

ABSTRACT

A 15-month-old full-term boy of African descent with an asymptomatic sickle cell trait presented with episodes of transient erythematous subcutaneous nodules involving the entire body except the face, since 2 weeks of age. The skin lesions evolved to areas of lipoatrophy and hyperpigmentation. An initial skin biopsy, studied at a different department at 2 months, was initially misinterpreted as subcutaneous fat necrosis of the newborn, despite the lack of the typical radiated crystals and needle-shaped clefts characterizing that entity. At 4 months of age, he developed systemic inflammatory manifestations, including fever, a new rash, significant periorbital edema, and failure to thrive. An extensive workup showed leukocytosis, hypercalcemia, elevated inflammatory markers, hypertriglyceridemia, and transaminitis. A new skin biopsy of the eyelid was diagnosed as neutrophilic lobular panniculitis with necrotic adipocytes. An initial whole-exome sequencing did not identify any causative mutations, but a WES reanalysis focused on autoinflammatory disorders was requested based on additional clinicopathologic data and revealed a mosaic intronic mutation in IKBKG c. 671+3 G > C. This mutation encodes an mRNA missing exon 5 resulting in NF-kB essential modulator (NEMO) Δ-exon 5-autoinflammatory syndrome (NDAS). NEMO-NDAS is one of the systemic autoinflammatory diseases that may appear as an unexplained panniculitis in young children, who should be monitored for immunodeficiency and/or autoinflammatory diseases. The differential diagnosis of autoinflammatory disorders should be considered in such cases incorporating the use of the whole-genome/exome sequencing in the investigation. The inhibitor of kappa-B kinase regulatory subunit gamma (IKBKG) is located on chromosome Xq28 and encodes the NEMO, a critical molecule upstream of NF-kB activation.