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Description

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder caused by gain of function mutations in the ACVR1 gene, leading to progressive heterotopic ossification of soft tissues. Early inflammatory flares can present as painful soft-tissue masses, which may mimic abscess or neoplasm on initial imaging. Misdiagnosis can result in unnecessary biopsies or surgery, which can exacerbate ossification. Prompt recognition of characteristic imaging findings can help prevent iatrogenic harm.

Patient Description: A 7-year-old boy with multiple congenital skeletal abnormalities presented with a new painful mass over the right lower neck and shoulder. He was initially seen at an outside urgent care and emergency department, where CT suggested possible soft-tissue neoplasm or abscess. He was afebrile and otherwise well. Due to diagnostic uncertainty and possible need for surgery, he was transferred to Helen DeVos Children's Hospital for further evaluation.    Imaging Findings: Overread of the CT showed an extensive edematous, infiltrative process in the deep posterior neck muscles without discrete mass, rim enhancement, gas, or calcification. Additional findings included progressive posterior spinal ankylosis (C4-T5) and symmetric proximal humeral pseudoexostoses, consistent with chronic skeletal manifestations of FOP. Correlation with prior imaging and history supported an acute inflammatory flare rather than neoplasm or abscess.

This case underscores the important role of radiology in identifying FOP in acute pre-ossification flares, particularly because initial imaging can be concerning for infection or neoplasm. Early and accurate recognition can prevent unnecessary and potentially harmful interventions. Additionally, this case provides a valuable educational example of how careful integration of current imaging findings with prior imaging and clinical history can help guide management in rare skeletal disorders.

Publication Date

5-8-2026

Disciplines

Radiology

Comments

2026 Research Day Corewell Health West, Grand Rapids, MI, May 8, 2026. Abstract 2062

Radiologic Recognition of Fibrodysplasia Ossificans Progressiva Avoids Potentially Harmful Biopsy

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