Histomorphometric analysis of sclerotic bone from idiopathic myeloid metaplasia (nine cases).

The osteosclerosis of idiopathic myeloid metaplasia was investigated by a histodynamic study of undecalcified bone from nine patients. In all cases osteosclerosis resulted from woven bone formation. In moderate osteosclerosis only intrabecular woven bone was observed, with osteoclastic hyperresorption, hyperosteoidosis with many osteoblasts, and an increased calcification rate. This may represent an early stage of the disease, osteosclerosis resulting from increased bone remodelling, with woven bone formation by osteoblasts. However, in extensive osteosclerosis both intratrabecular and medullary woven bone was observed, with moderate osteoclastic hyperresorption, hyperosteoidosis without osteoblasts and a very low calcification rate. The latter pattern could correspond to an advanced stage, and could result from stromal bone formation without osteoblasts. The classical histodynamic profile of osteomalacia was sometimes observed. The link between bone pain and possible osteomalacia remains vague.