Epidermoid cyst of the skull. A case observed for sixteen years.

Abstract

Epidermoid cysts of the skull are rare, only about 100 cases having been reported since the beginning of the last century. Standard texts on roentgen diagnosis of skull lesions describe the variable appearances of this interesting entity. On examination in September 1946, two years after the amputation, a lung nodule was detected in the left upper lobe, 6 cm. in diameter, consistent with metastatic tumor. The patient was referred to the VA Hospital in Memphis for treatment. There a metastatic bone survey, as part of a work-up for surgery, revealed an ovoid lytic lesion in the left Cholesteatoma, epidermoidoma, and “pearly” tumor are terms also applied to this condition. Because of unusual associated factors, the case to be presented here was observed over a period of sixteen years before surgical removal of the cyst. The varying radiographic appearances of the lesion in this patient at different stages of growth should contribute to a better understanding of its natural history. Case Report A 22-year-old white male was found to have an osteogenic sarcoma of the distal end of the left femur while in the Army. In August 1944, an amputation through the proximal third of the femur was carried out, and the patient was discharged from the Army to be followed at a Veterans Administration Hospital. parietal bone (Fig. 1). The lesion measured 1.5 × 2 cm., was smoothly regular in outline, and was surrounded by a margin of sclerotic bone. It was radiographically characteristic of a benign epidermoid cyst. Review of films of the skull taken while in the Army in 1944 indicated that it was present at that time and had not changed in size or appearance. There were no symptoms relative to its presence. A left upper lobectomy was done in October 1946. The lung nodule was characteristic histologically of metastatic osteogenic sarcoma. The patient was readmitted to the hospital in July 1947 because of the discovery of a second lung nodule in the left lower lobe, 4 cm. in diameter. A lobectomy was done, with pathological confirmation of metastatic tumor. The lesion in the skull at this time was unchanged in size or appearance. On readmission in November 1950, a cavitary tuberculosis lesion was detected in the right middle lobe. Sputum was positive for the tubercle bacillus on concentration and culture. The defect in the skull (Fig. 2) showed an increase in size, measuring 1.7 × 2.5 cm. In addition, the smoothly ovoid outline had now assumed a scalloped appearance. Its sclerotic border was uninterrupted. It was still asymptomatic. Under treatment with streptomycin, PAS, and pneumoperitoneum, the sputum and culture became negative and by the time of discharge in June 1951 the lung lesion had regressed to a small fibrotic density. In March 1960 the patient again entered the hospital, complaining of a left parietal mass with slow enlargement over the preceding year.