[Giant neurofibroma of the occipital scalp associated with lambda defect-case report (author's transl)].

Calvarial bone defect associated with a hugh neurofibroma in the region of the lambdoid suture was reported in a 42-year-old man with v. Recklinghausen's neurofibromatosis. An enlarging occipital tumor was first noted at age 4 similar to or approximately 5, and an operation was performed at age 12. Lambda defect was noted at that time, but the operative diagnosis was, apparently, "meningocele". Available literature was reviewed, and the significance of calvarial bone defect in the region of the lambdoid suture as a manifestation of v. Recklinghausen's disease was stressed. Lambda defect witn no sclerosing margin, particularly if associated with hypoplasia of the ipsilateral mastoid cells, has been known to represent the primary nature of the bone defect due to mesodermal dysplasia. In the present case, plain radiographs of the skull revealed abnormal sclerotic change around the bone defect. It is suggested that such an osteoblastic change may well indicate the secondary nature of the bone defect due to the presence of overlying neurogenic tumor.