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Abstract: Dermatofibroma is a proliferation of spindle cells located in the dermis. We used scanning electron microscopy to examine two histologically confirmed lesions and observed preserved collagen bundles in the perilesional area. In the lesional area, the collagen was denser, without formation of bundles. Higher magnification showed collagen with mesh-like appearance similar to stretched tufts of cotton. Very high magnification evidenced the tufts of cotton and spindle cells measuring 2 to 12 microns.

Abstract: We report the ultrastructural findings in a case of a 72-year-old black woman with confluent yellowish papules in the cervical region. She had no comorbidities. Ophthalmological examination, electrocardiogram, and echocardiogram were normal. Hematoxylin-eosin staining of the affected skin showed strong alterations in the mid-dermis with irregular clumps of eosinophilic material and loss of the normal parallel arrangement of collagen bundles. Orcein staining revealed that the elastic fibers lost their normal linear configuration, showing clump fragmentation, sometimes forming square structures. Transmission electron microscopy showed aberrant elastic fibers with an irregular outline and heterogenic inner structures. We also observed small elastic fibers. Collagen fibers showed a normal structure with irregular distribution. Scanning electron microscopy revealed important disorganization of collagen fibers and small stone-like deposits measuring around 5 µm associated with bigger structures ranging from 10-16 µm. Higher magnification revealed that these small stone-like structures were sometimes polyhedral-shaped or squared.

Abstract Cutis rhomboidalis nuchae was assessed in a 65-year-old patient. Optical microscopy showed basophilic agglomerations in the reticular dermis with decreased elastic fibers. Trans- mission electron microscopy showed elongated, curved and fragmented structures, and in their interior the presence of electron-dense lumps was reduced and irregular, similar to modified elastic fibers, whereas the collagen fibers had a normal aspect. Scanning electron microscopy showed deposits between the bundles of collagen, resembling pebbles or stones. These findings demonstrate that, at one stage of the disease, the collagen remains normal and the alterations are seen in the elastic tissue.