ABSTRACTS 285

assess, but it is a common problem confronted by oto- laryngologists. This review article examines the clinical characteristics and current investigations into the biol- ogy of keloid formation. It has been found that collagen synthesis in keloids is approximately 20 times greater than in normal unscarred skin. This is of interest in that the biochemical defect can be characterized and a phar- macologic means of reversing this process may be avail- able. Immunologic differences also exist among pa- tients with keloids. One group of investigators have found that extractable IgG from keloid tissue is signifi- cantly greater than that from skin of normal scars. Early reports have also suggested that growth factors may play a regulatory role in the formation of these lesions. Treatment of keloids is very frustrating and no single effective method is currently infallible. Several surgical approaches are available, with smaller lesions being ex- cised and closed primarily. Pressure dressings have been used, the idea being that pressure decreases blood flow to the scar, resulting in a reduced delivery of those factors necessary for scar formation. The authors of this article indicate that pressure can be an effective therapy for established keloids and as a prophylactic measure. X-ray treatment for keloids has been used in the past, but whether there is any current role for this modality is controversial. Several groups have used laser therapy in the treatment of keloids, but currently there is not enough data to support the routine use of this costly mode of therapy. Knowledge of wound healing and col- lagen metabolism continues to increase, suggesting that new advances in understanding keloids may be avail- able in the future. This is an interesting and thorough review article and should be examined by anyone deal- ing with this difficult problem.

The Emerging Epidemic of Melanoma and Squamous Cell Skin Cancer. AG Glass, RN Hoover. JAMA 1989; 262:2097-2100

Squamous cell carcinoma of the skin is common, but relatively unreported and unstudied. The current paper examines a large prepaid health insurance program serving more than 3,000 members in the Portland, OR, and Washington area. The investigators describe the ba- sic epidemiologic features of squamous cell carcinoma of the skin and compare it to melanoma. In the popu- lation examined, the incidence of both malignancies was increased relative to the general population. The incidence of squamous cell cancer of the skin increased by a factor of 2.6 in men and 3.1 in women, while the incidence of melanoma rose by 3.6 and 4.6 in men and women, respectively. Skin cancers of both types involv- ing the head and neck increased in parallel over the last 27 years. This increase in the incidence of both malig- nancies has gone undescribed until recently. The in- creased incidence of skin cancer may be a reflection of greater volitional exposure to sunlight by successive generations of middle-class Americans. This report em- phasizes the need to encourage individuals to protect themselves from ultraviolet radiation using sunscreens and also encourages the early detection and effective treatment of both squamous cell carcinoma and mela- noma of the skin.

Growth and Survival of Vascularized and Nonvascu- larked Membranous Bone: An Experimental Study. SP Barlett, LA Whitaker. Plast Reconstr Surg 1989; 84:783-788

Posttraumatic facial bone reconstruction and maxil- lofacial surgery often require the use of autologous bone grafts. Following any such grafting procedure there is a variable loss of bone substance due to absorption. The craniofacial skeleton is composed of membranous bone and a number of bone grafts used in this area are also membranous in origin. Recently, it has been reported that nonvascularized onlay membranous bone grafts undergo less resorption than endochondral grafts. This study was undertaken to define the indications for and the use of vascularized and nonvascularized membra- nous bone transfers. In addition, this paper compares the survival of these two bone types and their potential for growth in an experimental model. Two groups of rabbits were used and bone transfer was made both with vascularized and nonvascularized bone. In this model, vascularized and nonvascularized onlay mem- branous bone grafts in mature animals showed no dif- ference in survival. In contradistinction, immature an- imals showed a statistically significant difference in residual graft volume favoring vascularized over non- vascularized transfer. Experimental evidence to date demonstrates that vascularized and nonvascularized transfers in mature animals have an equal rate of “take,” whereas a growth advantage for the vascular- ized transfer is seen only in immature animals. This is an interesting experimental study that has implications for the use of onlay bone grafts in the craniofacial skel- eton of adults as well as of pediatric patients. In the majority of cases, nonvascularized onlay membranous grafts are well tolerated and have a good take in mature animals, whereas vascularized bone transfers are pre- ferred in immature animals.

Surgical Treatment of Thyrotoxic Exophthalmos. R Roncevic, T Jackson. Plas Reconstr Surg 1989; 84:754-760

According to these authors, conservative treatment of thyrotoxic eye disease has not always given satisfactory results. This paper describes a modified surgical tech- nique by which the bony bridge between the floor and lateral wall of the orbit is removed to produce a large orbitectomy. As much periorbital fat as possible is re- moved, producing a symmetrical decompression of the orbit. The claim is made that this is superior because, although the pathophysiology of the disease is inflam- mation of the extraocular muscles, the removal of fat adequately decompress the orbit. The authors further report that all patients in this small series showed a significant reduction in exophthalmos. Whether this or- bital decompression technique is a significant addition to the well-described methods in the literature remains to been seen with long-term follow-up. Most authors will agree that progression of thyrotoxic exophthalmos is common in this autoimmune disease. Only time will tell whether surgical decompression is adequate.