Chronic recurrent multifocal osteomyelitis masquerading as multifocal bone Langerhans cell histiocytosis in children: A case series from a tertiary cancer center

Chronic recurrent multifocal osteomyelitis (CRMO), also known as chronic non-bacterial osteomyelitis (CNO), is an autoimmune inflammatory bone disorder mainly affecting children and adolescents. The clinical presentation varies from mild, self-limiting unifocal bone inflammation, which is more common, to multifocal recurrent disease. CRMO can be misdiagnosed as multifocal bone Langerhans cell histiocytosis (LCH), infections, lymphoma, or metabolic bone disease. Clinical features are highly variable and not very specific. Most children experience vague aches and pains over prolonged periods but remain generally well and do not exhibit growth failure. In this article, we describe a case series of three children who presented with multifocal bone disease and were initially referred for LCH; however, detailed investigations confirmed the diagnosis of CRMO. The treatment options included non-steroidal anti-inflammatory drugs, corticosteroids, and disease-modifying anti-rheumatic drugs. Other treatment options included anti-tumor necrosis factor agents and bisphosphonates, similar to those used for autoimmune bone diseases. CRMO should be considered a differential diagnosis in children presenting with chronic, vague, and recurrent bony symptoms with or without systemic symptoms.