Characterization of hypertrophic osteoarthropathy in an identified skeleton from Évora, Portugal, using combined and comparative morphology and microscopy.

Hypertrophic osteoarthropathy (HOA) is a bone pathology that can be associated with a number of focal or systemic diseases, particularly those affecting the respiratory system. HOA is characterized by proliferative periostosis of the long bones, especially in their distal and periarticular regions. This report presents a probable case of HOA in the skeleton of an elderly Portuguese male from Évora, Portugal, who died in 1970. The skeleton was evaluated by morphological, radiological, and histological methods. We found bilateral periosteal proliferation of the tubular bones, remodeling of the phalanges of the feet, and new bone formation on rib visceral surfaces. Bone alterations are more severe on the left tibia and fibula, where lesions display a 'tree bark' appearance, leading to severe thickening of the diaphysis. Microscopically, we observed deposition of porous woven bone. Our evaluation also considers a differential diagnosis of the lesions, which includes melorheostosis, hypervitaminosis A, fluorosis, thyroid acropachy, tuberculosis, and treponematosis.