The infrequency of malignant disease in diaphyseal aclasis and neurofibromatosis.

The association of diaphyseal aclasis and neurofibromatosis with malignant neoplasms has been variously reported as between 5 and 28% of all cases, but malignant disease invariably presents at hospital and the true frequency from an unselected group is unknown. The current survey reviews not only hospital patients but also their affected relatives, with particular reference to malignant disease and the cause of death in all family members. A survey of 36 index patients and 80 known affected relatives with diaphyseal aclasis and 37 index patients and 33 known affected relatives with neurofibromatosis has been carried out. The observed proportions with associated malignant disease were 0.9% of all cases of diaphyseal aclasis and 4.3% of neurofibromatosis. The authors consider this is still too high an estimate in view of the number of persons in the families only mildly affected by the inherited disease who cannot be identified, although their malignant disease will be known. A more likely figure for malignant change in diaphyseal aclasis is calculated at 0.5% (or 1.3% of those over 21 years) and in neurofibromatosis 2.0% (or 4.2% of those over 21 years).