Melorheostosis: Clinical, radiological, and histopathological features with a literature review

Melorheostosis is a rare sclerosing bone dysplasia that can clinically and radiologically mimic common bone disorders, particularly in atypical presentations. Its heterogeneous manifestations and limited awareness among clinicians frequently contribute to diagnostic delays or misdiagnosis. We report the case of a 34-year-old woman with chronic forearm pain and a longstanding subcutaneous mass. She was initially misdiagnosed as having a metabolic bone disorder based on imaging and histopathology. However, subsequent evaluation with MRI and bone scintigraphy demonstrated eccentric cortical thickening and longitudinal sclerotic lesions involving the radius, olecranon, and first metacarpal. Normal biochemical markers and the absence of systemic involvement further supported a diagnosis of melorheostosis. Histopathological re-examination confirmed lamellar cortical bone with osteoblastic rimming but remained nonspecific. This case underscores the importance of considering melorheostosis in the differential diagnosis of sclerosing bone disorders, especially when radiographic features are ambiguous. It highlights the critical role of multimodal imaging in establishing an accurate diagnosis, while histopathology provides complementary but not definitive evidence. Importantly, melorheostosis may also serve as a window into bone physiology, illustrating aberrant osteogenesis and dysregulated cortical remodeling. A better understanding of its molecular basis, particularly MAPK pathway alterations, may ultimately facilitate more targeted and effective treatments.