FOP: still turning into stone


Fibrodysplasia ossificans progressiva (FOP) is a rare catastrophic genetic condition of extraskeletal (heterotopic) ossification. One in every two million people is affected worldwide, with no ethnic, racial, gender, or geographic predisposition. Most cases of FOP arise from a spontaneous missense mutation in the gene encoding bone morphogenic protein (BMP) type II receptor (ACVR1/ALK2). Affected individuals are normal at birth apart from malformed great toes. Onset of clinical symptoms is usually in the first decade of life, presenting with episodic emergence of painful rapidly appearing tumor-like soft tissue swellings (flare-ups). Heterotopic bone replaces the skeletal muscles, tendons, ligaments, and connective tissue at the site of the damage through a process of endochondral ossification, causing fixation of joints and permanent limitation of motion. Most affected individuals are confined to wheelchair in the third decade of life. Worldwide rate of misdiagnosis of FOP is very high; clinicians often fail to associate the two classic clinical features of FOP: rapidly developing soft tissue swellings and the abnormal great toes. The current case presents a previously undiagnosed 39-year-old FOP patient, sadly a victim of lack of clinical awareness of this rare condition. As a result of repetitive iatrogenic harm, he has tragically “turned into stone.”

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Correspondence to Saba Jafarpour.

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The Patient was incapable of sitting or bending. He needed assistance to lie down. (MPG 5743 kb)

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Taslimi, R., Jafarpour, S. & Hassanpour, N. FOP: still turning into stone. Clin Rheumatol 34, 379–384 (2015).

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  • Fibrodysplasia ossificans progressiva (FOP)
  • Heterotopic ossification
  • Medical error
  • Myositis ossificans