3.2.4 Histopathology Seven biopsies were taken of neck lesions and one of an axillary lesion during the third to fourth week after exposure on the Rongelap people. The lesions biopsied at that time werein the hyperpigmented stage with Jitthe or no desquamation (shedding) having occurred. Most of these biopsies were taken from individuals who showed lesions of greater than average severily. A second group of biopsies from the Rongelap group (repeated in three individuals) were taken; four at the seventh week post-exposureand five at the eighth-week period. These weretaken from the neck and antecubital fossae. Al! of these lesions had desquamated and the depigmented skin had repigmented to a dusky, gray color with some thickening (“orange-peel” appearance) of the skin. Biopsies were not taken from open lesions or from the feet for fear of infection, All biopsy wounds healed rapidly with no secondary complications. The microscopic findings are summarized as follows: Early biopsies. 3rd to 4th week, Epidermis Trangepidermal damage was noted with a few intervening arcades showing less damage (Plates 3.18 and 3.19). ‘The epidermis in the most extensively involved areas showed consider able atrophy with flattening of (he rete pegs. In places the epidermis was reduced to a thickness of 2 to 3 cells (Plates 3.20 and 3.21). The cells of the malpightan layer showed pleomorphic nuclei, pyknosis and cytoplasmic halos, giant cells and in a few instances multinucleated cells. Pyknosis of cells of the basal layer was commonly seen. Focal disorganization of the malpighian and basal layers was usually present in the more extensively damaged arcades. Cells laden with pigment were frequently present throughout the epidermis and intercellular pigment was noted in some sections. The stratum granulosum was usually atrophic or even absent. Imperfect keratinization with parakeratosis was visible in all sections. Hyperkeratosis was also seen. The stratum corneum was loosely fibrillated. The arcades of minimal damage were usually found in areas where sweat ducts approached the epidermis (Plate 3.19). There was an apparent increase in the numbei of cells and mitotic figures in the neck of the ducts and the adjoining areas where regeneration was underway. In these areas the stratum granulosum was near normal width and pigmentation of the basal cells noted in the more severely damaged areas was lacking. Changes in the dermis were largely confined to the pars papillaris (F'ates 3.18 through 3.21). Mild edema in some cases was noted. Capillary loops were often indistinct and when discernible they frequently were associated with an increased number of pericytes. The endothelial cells showed swelling and were polygonal in shape. Telangiectatic changes (dilated blood vessels) were noted in areas where the overlying epidermis showed greatest damage with lymphocytic infiltration surrounding the telangiectatic spaces. Chromatophores, filled with melanin pigment, were prominent in the superficial dermis. The fine elastic fibrils running into the pars papillaris were often altered or absent. Little if any damage was seen below the superficial pars reticularis. The hair follicles were narrow (Plate 3.22) and in most instances devoid of shafts in this region. There was some telangiectasis of the capillary spaces bounded by lymphocytes and monuclear phagocytes in the superficial pars reticularis. Some of the large elastic fibers in this region showed slight swelling in some instances. No damage to fibrocytes or collagen fibers was noted. Second series, 7th and 8th weeks post-exposure. Epidermis In general, reparative processes ofthe epidermisappearedto have been fairly good, ex~ cept for a few persistent areas of atrophy with narrowing of the epidermis and finger-like downgrowths of the stratum malpighii (Plate 3.24), These occurred in areas of greatest epidermal narrowing and the cells showed rather prominent pigment content. There were many outward epidermal excrescences covered by thickened stratum corneum which was still loosely laminated-~ such phenomenun producing a wrinkled appearance which probably accounted for the “orange-peel” like appearance of the skin noted grossly in the areas biopsied (Plate 3.22). In almost all instances the basal layer was intact with little or no disorganization noted. There were a few scattercd areas in which occasional epithelial cells with pyknotic nuclei and perinuclear cytoplasmic halos occurred in the stratum granulosum and maipighian layers (Plate 3.23). There were occasional arcades in which the epidermis, particularly the stratum granulosum, appeared tu be actually widened. These occurred almost predominantly in relationship se uvee 38