Think about the 'C' (in custard and crackers).

Area of Science:

• Pediatrics
• Rheumatology
• Dermatology

Background:

• A 9-year-old girl with a history of chronic recurrent multifocal osteomyelitis (CRMO) and autistic spectrum disorder (ASD) presented with worsening leg pain and a petechial rash.
• Her medical history included CRMO diagnosed at age 3 with involvement of multiple joints, previous bisphosphonate treatment, and a highly restricted diet (custard and crackers).

Observation:

• The patient presented with a 3-month history of leg pain, inability to weight-bear, and a 10-day history of a widespread petechial rash, most prominent on the lower extremities.
• Physical examination revealed tenderness in the knees and ankles, with small effusions in the ankles. She was afebrile.
• Laboratory investigations showed mild hypochromic anemia, with normal platelet counts and coagulation parameters. C-reactive protein (CRP) was elevated at 16.

Findings:

• Radiographs and MRI of the knee demonstrated findings consistent with CRMO exacerbation.
• The combination of petechial rash and bleeding gums in the context of leg pain and CRMO raised concerns for other underlying conditions, particularly those related to nutritional deficiencies or hematological disorders.

Implications:

• This case underscores the importance of considering nutritional deficiencies and hematological conditions in the differential diagnosis of children with ASD, CRMO, and unusual symptoms like petechial rashes and bleeding gums.
• It highlights the diagnostic challenges posed by restricted eating patterns in children with ASD and the need for a multidisciplinary approach to manage complex cases involving chronic inflammatory conditions.