Histopathological characteristics are instrumental to distinguish monomorphic from polymorphic maculopapular cutaneous mastocytosis in children. (11th July 2022)

• Record Type: Journal Article
• Authors: Hermans, Maud A. W.; Pasmans, Suzanne G. M. A.; Arends, Nicolette J. T.; van den Bosch, Thierry P. P.; van Daele, Paul L. A.; van Doorn, Martijn B. A.; Huisman, Elise J.; Mooyaart, Antien L.; Damman, Jeffrey
• Is Part Of: Clinical and experimental dermatology. Volume 47:Number 9(2022)
• Page Start: 1694
• Page End: 1702
• Publication Date: 2022-07-11
• Subjects: Skin -- Diseases -- Periodicals; 616.5
• DOI: 10.1111/ced.15262
• Languages: English
• ISSNs: 0307-6938

Abstract

Abstract: Background: Mastocytosis is characterized by the accumulation of mast cells (MCs) in the skin or other organs, and can manifest at any age. A significant number of paediatric mastocytosis cases persist after puberty. In particular, monomorphic maculopapular cutaneous mastocytosis (mMPCM) is often persistent and associated with systemic mastocytosis. However, clinical differentiation of MPCM from polymorphic (p)MPCM can be difficult. Aim: To identify histopathological features that can help to distinguish mMPCM from other subtypes of paediatric mastocytosis. Methods: This was a retrospective study using skin biopsies from patients with any subtype of mastocytosis. The localization and density of the MC infiltrate, MC morphology and expression of aberrant markers were evaluated and correlated with clinical characteristics. Results: In total, 33 biopsies were available for evaluation from 26 children [(10 with mMPCM, 5 with mastocytoma, 3 with diffuse cutaneous mastocytosis (DCM), 8 with pMPCM)] and 7 adults with MPCM. The MC number was increased in all patients, but was higher in children than adults ( P < 0.01). The presence of mMPCM was associated with sparing of the papillary dermis from MC infiltration, whereas MC density in the papillary dermis was highest in pMPCM and DCM ( P < 0.01). The positive predictive value of the presence of a reticular MC infiltrate for mMPCM was 72.7% (95% CI 51.4–87.0), and the negative predictive value was 83.3% (95% CI 42.2–97.2). There were no relevant differences in the expression of CD2, CD25 or CD30 between the different subtypes. Conclusion: Skin histopathology might enhance the phenotypical differentiation of mMPCM from other subtypes in children, thereby increasing the accuracy of one's prognosis. Abstract : In this study, we found that paediatric monomorphic maculopapular cutaneous mastocytosis (mMPCM) was associated with a specific histopathological pattern compared with other paediatric subtypes of mastocytosis such as polymorphic (p)MPCM. Paediatric mMPCM was characterized by a predominantly reticular situated MC infiltrate with sparing of the papillary dermis. This was similar to the pattern seen in adult‐onset MPCM; however, total MC counts in lesional skin were significantly higher in children compared with adults. Histopathology might be a useful addition to the clinical phenotype and laboratory parameters to distinguish mMPCM from pMPCM in children.