Button sequestrum of the skull.

Abstract

The term “button sequestrum” was coined by Wells (7) to describe an unusual roentgen appearance he had encountered in eosinophilic granuloma of the calvaria. The term refers to a radiolucent defect with a central nidus of intact bone. A similar roentgen appearance had been previously reported by Meng and Wu (3) and Tirona (6) in tuberculosis of the skull. In addition to eosinophilic granuloma and tuberculous osteitis, we have observed button sequestrum of the skull in two other conditions. Examples of each of these are presented in this paper. Eosinophilic Granuloma Case I: E. W., a 28-year-old Caucasian woman, was seen at the Cincinnati General Hospital in June 1965. Approximately eight months earlier, the patient began to experience occipital swelling and pain. Skull roentgenograms at another hospital (Fig. 1) demonstrated a lytic occipital defect with a “button sequestrum.” Biopsy of the scalp and calvarial lesions revealed eosinophilic granuloma. Postoperative radiation therapy was administered to the lesion over a seven-day period (1,500 R air dose; 250 kV, 20 mA, half value layer 4.05 mm Cu, and a 50 cm target-skin distance). The occipital defect has persisted although the central sequestrum has disappeared. A vaginal hysterectomy was performed in February 1967 for preinvasive carcinoma of the cervix. Histologically, there were aggregates of histiocytes and a large number of eosinophils in the uterus, a picture similar to that of the occipital lesion and consistent with eosinophilic granuloma. Biopsy of a lytic defect in the medial end of the right clavicle in August 1967 also revealed eosinophilic granuloma. Comment: The button sequestrum of eosinophilic granuloma described by Wells was ob-served in 4 men, all in their thirties. As with our patient, all had pain or tenderness over the area of involvement. There were no follow-up studies. Ochsner (4) recorded cranial involvement in 6 of 20 patients with eosinophilic granuloma. In the only case with a “central button of bone,” the sequestrum disappeared during six months of observation. The granulomatous defect in the skull may on occasion remit spontaneously. Irradiation frequently promotes healing, but re-ossification is not an invariable result (2). In our patient, the sequestrum disappeared after biopsy and radiation therapy; however, the osseous defect persisted relatively unchanged. Eosinophilie granuloma frequently begins in the diploe and destroys both tables of the skull. Asymmetrical involvement of the 2 tables results in the bevelled appearance of the margins of the lesion. Incomplete destruction of either table may be the cause of the sequestrum-like appearance. Histologic Appearance The gross appearance of inverting nasal papilloma is similar to that of ordinary infectious or allergic nasal polyps. Histologic examination is necessary for a definitive diagnosis. A pronounced thickness and infolding of the epithelial covering is the most characteristic finding on histologic examination (Fig. 1). Despite the great epithelial proliferation, mitotic activity is not increased, and everywhere the basement membrane is intact. A definite basal layer of cells is always present. The epithelium may be of ciliated columnar, transitional-cell, or squamous-cell type. That of the transitional-cell and squamous-cell types is thought to represent metaplasia from the normal ciliated columnar epithelium of the respiratory tract.