Three-dimensional ultrastructural study of molluscum contagiosum in the skin using scanning-electron microscopy

Scanning electron microscopy of molluscum contagiosum

Molluscum contagiosum is a disease caused by a poxvirus. It is more prevalent in children up to 5 years of age. There is a second peak of incidence in young adults. In order to examine its ultrastructure, three lesions were curetted without disruption, cut transversely with a scalpel, and routinely processed for scanning electron microscopy (SEM). The oval structure of molluscum contagiosum could be easily identified. In its core, there was a central umbilication and just below this depression, there was a keratinized tunnel. Under higher magnification, a proliferation similar to the epidermis was seen. Moreover, there were areas of cells disposed like a mosaic. Under higher magnification, rounded structures measuring 0.4 micron could be observed at the end of the keratinized tunnel and on the surface of the lesion.

Giant molluscum contagiosum in AIDS

A 31-year-old man, an intravenous drug user and in an advanced stage of acquired immune deficiency syndrome (AIDS), was admitted in our Department for the treatment of skin lesions that had been diagnosed as molluscum contagiosum (MC). The clinical examination revealed the presence of multiple nodular lesions, some of which were notably large and whose color resembled that of normal skin. These lesions were localized mainly to the face, and in particular on the forehead, glabellar, malar, beard, submandibular, and neck regions (Fig. 1). Smaller, crateriform lesions were detected on the hands and the upper limbs. The lymphocyte subsets ratio was 0.02, with a CD4+ T cell count of 13 cells per mm3 (1%) and a CD8+ T cell count of 624 per mm3 (48%). The patient also had leukopenia (1690 WBC per mm3), moderate macrocytic anemia, elevation of transaminases (SGOT 105 U/L, SGPT 114 U/L) and of immunoglobulins (IgG 2660 mg/dL), and a decrease of C3 (44.2 mg/dL) and C4 (16.6 mg/dL). Histologic examination revealed the presence of typical MC lesions. In addition to an important acanthosis, it was possible to detect pyriform lobules of perfectly delineated epidermal cells, radially separated by fibrous septa that merge towards the central crater. The characteristic MC eosinophil bodies were observed in infected cells (Fig. 2). The lesions were treated with cryosurgery by spray. Many courses of therapy were given with intervals of 2-3 weeks. Every session consisted of two cycles of rapid freezing followed by a slow thaw. Many lesions disappeared with this treatment, and others were reduced in size, but total destruction of all lesions was not achieved (Fig. 3).