Fibrodysplasia ossificans progressiva: initial presentation with a preosseous lesion of the scalp and its MRI appearance

Abstract

This case subject is a 1-year-old girl presenting with recurrent diffuse soft-tissue swelling of the scalp and periorbital region. Her family denied any known history of trauma. There was no obvious discoloration or local heat at the lesion. Magnetic resonance imaging (MRI) revealed diffuse soft tissue swelling of the scalp manifesting as high signal intensity on T2-weighted images and low signal intensity on T1-weighted images with diffuse enhancement after gadolinium-contrast administration. Biopsy yielded inconclusive pathological results. Fibrodysplasia ossificans progressiva (FOP) was not suspected until malformation of the patient's toes was noticed. The scalp lesion underwent spontaneous regression, and subsequent radiographs of the chest and cervical spine revealed heterotopic ossifications of the neck and thorax. Early diagnosis of FOP is vital because trauma, unnecessary biopsy and intramuscular injection are known to cause acceleration of heterotopic ossifications. Previous studies reported diffuse soft tissue swelling at the posterior neck, thoracic wall or paraspinal region as preosseous lesions of FOP (Shiva Kumar et al. Neurology. 2010;74(6):e20, Merchant et al. Pediatr Radiol. 2006;36(10):1108-11, Hagiwara et al. AJR Am J Roentgenol. 2003;181(4):1145-7). To our knowledge, diffuse soft tissue swelling of the scalp as a preosseous lesion of FOP and associated MRI findings have not yet been reported. We believe that awareness of preosseous lesions presenting as diffuse soft tissue swelling, in addition to shortening and valgus deformity of the great toes, is an important diagnostic clue for establishing FOP.

Young woman who presents with shortness of breath

“…Some studies have shown the importance of pre-osseous lesions in the early diagnosis of FOP. These lesions have been described as areas of diffuse soft tissue swelling on MR images, which exhibit low T1 and high T2 signal, with contrast enhancement, in the muscles, intermuscular planes, subcutaneous tissue, or along the fascial planes without infiltrating into the surrounding muscles [5][6][7]. In contrast to most neoplasms, FOP pre-osseous lesions appear suddenly and then change size and shape rapidly, often in a matter of hours.…”

“…Rotatory kyphoscoliosis of the spine is a late complication of the disease and is the result of unilateral osseous bridge along the spine prior to skeletal maturity. Other common skeletal manifestations include short thumbs, proximal medial tibial osteochondromas, neurosensory hearing loss, conductive hearing loss due to middle ear ossification, and short and broad femoral necks [3][4][5].…”

“…Therefore, early diagnosis and minimizing the trigger factors causing disease progression such as immunizations, bruises, falls, or viral illnesses, are crucial in these patients. Clinical management remains symptomatic [3,5,11].…”

Fibrodysplasia ossificans progressiva: Basic understanding and experimental models

“…Though bone formation is episodic, 243 X-rays can reveal abnormal osteogenesis. FOP cannot be diagnosed prenatally (22).…”

Diagnostic Value of Magnetic Resonance Imaging in Fibrodysplasia Ossificans Progressiva

“…MRI provides high soft tissue contrast and is able to detect edema, a potential marker of inflammatory stages in FOP . MRI is currently used in FOP to evaluate the presence of edema early in flare‐ups .…”