Giant plexiform neurofibroma of the back.

Complete excision of a giant neurofibroma can be technically difficult. Thorough preoperative planning with magnetic resonance imaging, computed tomography, and arteriography are indicated to define the extent of the mass and to facilitate operative planning. By following the treatment guidelines discussed in this case report, the authors feel that these tumors can be excised safely with minimal morbidity.

Three-dimensional reconstruction of the human fetal philtrum.

The anatomy of the philtrum is incompletely understood because it is difficult to analyze three-dimensionally. Previous anatomic studies suggested that the philtral ridges are formed by the dermal insertion of the orbicularis oris muscle and musculis nasalis decussating across the midline, with the philtral dimple an area of few muscular insertions. This theory is inconsistent with the usual finding of a normal-appearing philtrum contralateral to the cleft in patients with unilateral cleft lip. Using a microcomputer and three-dimensional software, we have created a three-dimensional model of the philtrum from digitized images of sequential transverse histological sections from a third-trimester fetus. Our studies demonstrate that the philtral ridges are formed by thickened dermis and dermal appendages. The labial levators are the predominant muscles associated with the philtrum throughout its length; their fibers insert into the dermis lateral to the philtral ridges. Crossing muscle fibers of the orbicularis oris pars marginalis only appear below the vermilion-cutaneous junction, caudal to the philtral ridges.

Cyclosporin A and the thymus. Immunopathology.

Cyclosporin A (CsA) is known to diminish the size of the thymus, especially the thymic medulla. The significance of these changes is not presently understood. This study reveals several immunopathologic changes induced in the thymic medulla by CsA (15 mg/kg/day). The weight and relative size of the thymus dramatically and rapidly involutes, with marked changes observed in 1 week. The medullary thymocytes show segregation of rat T-cell phenotypes as seen in control rats, but the number of such cells is markedly reduced in accordance with the medullary remnant. This is consistent with a maturational arrest of thymocytes. The medullary epithelium was assessed directly by irradiating the control or CsA-treated rats 2 days prior to sacrifice. The epithelium of Hassall's corpuscles was essentially absent in CsA-treated rats but prominent in control rats. The cortical epithelial cells were preserved. Stains for Ia antigen with the anti-OX4 antibody show little change in expression by cortical epithelium, but a marked reduction in the Ia+ medullary cells in the thymocyte purged rats. All of these changes were reversible in the normal rat after cessation of CsA, with near normal recovery in 3 weeks. No morphologic or immunopathologic changes were noted in the cortical thymocytes. These cells did, however, acquire CsA receptors, as detected by the binding of fluorescent dansylated CsA.