Progressive osseous heteroplasia in a 10-year-old male child

Abstract

We report a sporadic case of progressive osseous heteroplasia (POH) in a 10-year-old male child who developed progressive ossification of the skin and deep connective tissue. The condition needs to be distinguished from other causes of childhood heterotopic ossification, such as fibrodysplasia ossificans progressiva, pseudohypoparathyroidism, and pseudopseudohypoparathyroidism. The cause of POH is an inactivating GNAS1 (guanine nucleotide-binding protein alpha-stimulating activity polypeptide 1) mutation caused only by paternal inheritance of the mutant allele. Most cases are sporadic and only 2 instances of familial transmission have been documented, suggesting an autosomal dominant mode of inheritance with possible somatic mosaicism. The condition is associated with progressive superficial to deep ossification, progressive restriction of range of motion, bleak prognosis, and recurrence if excised.

Keywords: GNAS1 mutation; heterotopic ossification; subcutaneous ossification.

Figure 1

Clinical photograph showing hard cutaneous coalesced plaques over the left shoulder

Figure 2

Clinical photograph showing hard cutaneous coalesced plaques over the left elbow

Figure 3

X-ray of left arm with shoulder joint anteroposterior view showing diffuse cocoon-like web of heterotopic bone

Figure 4

X-ray of left forearm with elbow joint (anteroposterior and lateral views) showing ossification in the dermis and subcutaneous tissue in February 2010

Figure 5

X-rays of forearm with elbow joint (anteroposterior and lateral views) showing ossification in the dermis, subcutaneous tissue, and muscles