A child is brought to the orthopaedics OPD with a deformity in the lower limb and hyperpigmented skin lesions. The x-ray findings are suggestive of the diagnosis. What is the most likely diagnosis?

Options

1. Non-ossifying fibroma
2. Fibrous dysplasia
3. Paget's disease
4. Osteogenesis imperfecta

Correct Answer

Fibrous dysplasia

Explanation

The combination of bone deformity and hyperpigmented skin lesions (café-au-lait spots) is characteristic of Fibrous Dysplasia, particularly McCune-Albright syndrome when associated with: 1) Polyostotic fibrous dysplasia, 2) Café-au-lait spots with irregular "coast of Maine" borders, 3) Endocrine abnormalities (precocious puberty). X-ray shows: "ground glass" appearance, shepherd's crook deformity of proximal femur, expansion of bone with thinned cortex. It is caused by GNAS gene mutation. Non-ossifying fibroma is usually asymptomatic and incidental, Paget disease occurs in elderly, and Osteogenesis imperfecta presents with multiple fractures and blue sclera.

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