3.2.4 Histopathology Seven biupsies were taken of neck lesions and one of an axillary leston during the third to fourth week after exposure on the Rongelap people. The lesions biopsied at that time were in the hyperpigmented stage wsth little or no desquamation (shedding) having occurred. Most of these biopsies were taken from individuals who showed lesions of greater than average geverity. A second group of biopsies from the Rongelap group (repeated In three individuals) were taken; four at the seventh week post-exposure and five at the eighth-week period. These were taken from the neck and antecubital fossae. All of these legions had desquamated and the depipmented 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 fromthe feet for fear of infection, AIL biopsy wounds healed rapidly with no secondary complications, The microscope findings are summarized as follows: Early biopsies 3rd to 4th week. Epidermis Transepidermal damage was noled 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 wilh flattening of (he rete pegs. In places the epidermis was reduced to a thickness of 2 te 3 cells (Plates 3.20 and 3.21). The cells of the malpighian layer showed pleomorphic nuclei, pyknosts and cytoplasmic halos, giant cells and in a few instances muitinucleated cells. Pyknosis of cells of the basal layer was commonly seen. Focal disorganization of the mal- pighian 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 parakeratosigs 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 numbe: of cells and mitotic figures in the neck of the ducts and the adjoining areas where regeneration was underway. In these areas the sitraium granulosum wag 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 tu the pars papillaris (F'ates 3.18 through 3.21). Mild edema tn 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 blecd vessels) were noted in ureas where (he overlying epidermis showed greatest damage with lymphocytic infiltration surrounding the telangiectatic spaces. Chromatophores, filled with melanin piygiment, were prominent in the superficial dermis. The fine elastic fibrils running into the pars papillaris were often altered or absent. Little if any damaye was seen beluw the superficial pars reticularis. The hair follicles were narrow (Plate 3.22) and in most instances devoid of shafts tn 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, Tth and 8th weeks post-exposure, Epidermis in general, reparative processes of the epidermis appeared to have been fairly good, ex- cept fur a few persistent areas of atrophy with narrowing of the epidermis and finger-like downyrowths of the stratum malpighii (Plate 3.24). These occurred in areas of greatest epidermal narrowing and the celis showed rather prominent pigment content. There were many outward epidermal excrescences covered by thickened stratum corneum which was still loosely laminaled-- such phenomenon producing a wrinkled appearance which probably accounted for the ‘‘orange-peel” like appearance of the skin noted yrossly 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 scattered areas in which occasional epithelial ceils with pyknotic nuclei and perinuclear cytoplasmic fulos occurred in the stratum granulosum and malpighian layers (Plate 3.23). There were occasional arcades in which (he epidermis, particularly the stratum granulosum, appeared to be actually widened. These occurred almost predominantly in relationship 38