Dermatology: Practical and Conceptual Letter | Dermatol Pract Concept 2018;8(4):9 297 DERMATOLOGY PRACTICAL & CONCEPTUAL www.derm101.com Introduction Chronic recurrent multifocal osteomyelitis (CRMO) is a rare, noninfectious, inflammatory bone disease, which occurs mainly in childhood [1]. We present a case of CRMO and palmoplantar psoriatic skin lesions in a 12-year-old girl. Case Presentation A 12-year-old girl presented with recurrent erythematous pal- moplantar plaques and pustules. She also complained about pain in her left ankle that started 7 months earlier. Previous magnetic resonance imaging (MRI) had consistently revealed a multifocal bone edema of the left foot. Symptoms of weak- ness, fever, and morning stiffness were absent. The family history was unremarkable. Physical examination revealed well-demarcated erythema- tous plaques with remnants of dried pustules in a palmo- plantar distribution (Figure 1). The active range of motion of the left upper ankle joint was painfully decreased by 50%. Laboratory results showed a slight increase of inflammation parameters, including c-reactive protein level and erythrocyte sedimentation rate. Antinuclear antibody level, rheumatoid factor, HLA-B27, and Lyme disease testing were negative. Serial MRIs revealed fluctuating T2 hyperintensities and T1 hypointensities involving the left talus, calcaneus, and Chronic recurrent multifocal osteomyelitis with psoriatic skin manifestations in a 12-year-old female Andreas Epple1, Judith E. Paffhausen1, Christine Fink1, Alexander Enk1, Oliver Sedlaczek2, Holger A. Haenssle1 1 Department of Dermatology, University Hospital Heidelberg, Ruprecht Karls University Heidelberg, Germany 2 Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Ruprecht Karls University Heidelberg, Germany Key words: childhood, chronic recurrent multifocal osteomyelitis, palmoplantar pustular psoriasis, diagnosis Citation: Epple A, Paffhausen JE, Fink C, Enk A, Sedlaczek O, Haenssle HA. Chronic recurrent multifocal osteomyelitiswith psoriatic skin manifestations in a 12-year-old female. Dermatol Pract Concept. 2018;8(4):297-298. DOI: https://doi.org/10.5826/dpc.0804a09 Received: February 8, 2018; Accepted: March 15, 2018; Published: October 31, 2018 Copyright: ©2018 Epple et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: None. Competing interests: The authors have no conflicts of interest to disclose. All authors have contributed significantly to this publication. Corresponding author: Prof. Dr. Holger Haenssle, Department of Dermatology, University Hospital Heidelberg, Ruprecht Karls University Heidelberg, Neuenheimer Feld 440, 69120 Heidelberg, Germany. E-Mail: holger.haenssle@med.uni-heidelberg.de Figure 1. Well-demarcated erythematous scaly plaques with rem- nants of dried pustules on the left sole of the patient. [Copyright: ©2018 Epple et al.] 298 Letter | Dermatol Pract Concept 2018;8(4):9 accumulation of neutrophils. Thus IL-1β seems to play a key role in both CRMO and PPPP. Conclusion CRMO should be treated interdisciplinarily, and NSAIDs should be the medication of first choice. Skin lesions may be alleviated by topical steroids. Moreover, bisphosphonates, TNF antagonists, IL-1-inhibitors, sulfasalazine or metho- trexate have been described as effective. Fortunately, our patient showed a complete remission 2 years after the onset of symptoms, which is also observed in 30% to 40% of reported cases. In summary, we describe a rare case of CRMO initially presenting as PPPP with joint pain. Dermatologists and pedia- tricians should be familiar with the association of CRMO and PPPP in children to lead the way to correct diagnosis and treatment. References 1. Giedion A, Holthusen W, Masel LF, Vischer D. [Subacute and chronic “symmetrical” osteomyelitis]. Ann Radiol (Paris). 1972;15(3):329-342. 2. Bissonnette R, Fuentes-Duculan J, Mashiko S, et al. Palmoplantar pustular psoriasis (PPPP) is characterized by activation of the IL- 17A pathway. J Dermatol Sci. 2017;85(1):20-26. metatarsal bones with undulating discrete joint effusion in the left upper ankle joint (Figure 2a-d). Additionally, synovial thickening of the left talocalcaneonavicular joint was noticed. T1-weighted images after contrast application were acquired at several MR-measurements over the course of 1 year, mainly reflecting the edema seen as T2 hyperintensities. Based on these results, the diagnosis of CRMO accom- panied by palmoplantar pustular psoriasis (PPPP) was made. Treatment with oral nonsteroidal anti-inflammatory drugs (NSAIDs) and topical mometasone furoate 0.1% cream was initiated. CRMO was first described by Giedion et al in 1972. It pri- marily occurs in the distal metaphyses of long tubular bones [1]. The involvement of the calcaneus, as described herein, was rarely reported. PPPP is found in approximately 15% of CRMO patients. The pathophysiology of CRMO is not well understood. Recent studies of CRMO patients described a reduced production of interleukin (IL) 10 by monocytes. This impairment may result in an increased activation of the Nod-like receptor family pyrin domains containing protein 3 inflammasome (NLRP3) leading to an enhanced expression of IL-1β, which has a role in osteoclast activa- tion via receptor activator of nuclear factor kappa-B ligand (RANKL) stimulation. Bissonnette et al [2] described high levels of IL-1β and IL-17A in patients with PPPP leading to a secondary chemokine production of keratinocytes with Figure 2. Serial MRIs over the course of 12 months (a-d) with fat suppressed T2-weighted images showing the fluctuating hyperintensities of the left ankle involving the calcaneus, talus, and metatarsal bones with an undulating joint effusion in the left upper ankle joint. The date of each MRI is indicated in the top row of images. [Copyright: ©2018 Epple et al.]