Background: The pattern of distribution of skin diseases remains one of the most elusive problems in dermatology, particularly when multiple pathologies are involved and coexistence of patterns is present. Most skin diseases show a predilection for certain body areas and are located in characteristic patterns. Many dermatoses exhibit lesions in a segmental fashion concomitantly with disseminated patterns. Sometimes the sites of predilection are inexplicable. Objectives: The main purpose of this paper is to give an overview on the peculiar arrangement of cutaneous lesions in both congenital and acquired skin disorders as well as reactive phenomena in vulnerable areas, in order to better recognise them clinically and understand their pathogenesis. Methods: Based on personal observations and a review of literature, this paper summarises the basics in understanding the patterned distribution of skin lesions, highlights the significance of the lines of Blaschko and their relationship with mosaicism, and describes some of the reactive skin phenomena. Results: Skin mosaicism plays a crucial role in the distribution and arrangement of skin lesions, as demonstrated by recent advances in genetic research in an increasing number of various skin diseases.
The reverse isotopic response is a rarely encountered phenomenon. The spared lesions are various and mainly inflammatory in nature, with herpes zoster infection being the most common. A novel case of Stevens-Johnson syndrome triggered by carbamazepine sparing the skin area previously affected by herpes zoster infection in a 39-year-old Indian female with systemic lupus erythematosus is documented. Several features as well as possible pathomechanisms that bear discussion have emerged from this case documentation. These may be related to the virus immunity, the underlying autoimmune disease (systemic lupus erythematosus) and/or drug metabolism.
CASE REPORTA 1-week-old African infant male was admitted with an unusual constellation of findings. He was born after an uncomplicated, full-term first pregnancy of a 22-year-old mother. His parents were healthy and unrelated. The mother denied taking any medication during pregnancy. The infant was alert and did not appear ill.On examination several abnormalities were noted, including generalized hypertrichosis, most pronounced over the mid-back (Fig. 1), a dysmorphic facies with bilateral ectropion, hypertelorism, macrostomia, abnormally shaped ears, bulbous nose, and sparse eyebrows and eyelashes (Fig. 2). He also had hypoplasia of the nipples, transposition of the scrotum (shawl scrotum) (Fig. 3), club feet, a short neck, and laxity of the skin.A skin biopsy specimen from the right thigh showed an atrophic, slightly orthohyperkeratotic epidermis, and a thin reticular layer of dermis. Staining for elastic fibers showed a diminution in number and fragmentation (Fig. 4). The karyotype was normal. Radiographic examination of the axial skeleton, skull sonar, and abdom-inal echography were normal. Laboratory tests including full blood count, serum urea and electrolytes, serum proteins, liver enzymes, and glucose had normal results.
Merkel cell carcinoma (MCC) is a rare cutaneous neoplasm of presumed neuroendocrine origin, with aggressive behavior and poor prognosis, that tends to have an increased incidence among elderly Caucasians and immunosuppressed individuals. MCC is either associated with a clonal integration of the Merkel cell polyoma virus into the host genome or with genomic alterations caused by chronic UV exposure. Tumors of either carcinogenesis show epithelial, neuroendocrine, and B-lymphoid lineage markers. HIV-infected African albinos have a higher risk of developing skin cancers, including MCC, in comparison with the general population. We report a case of MCC of the head in a young albino woman with a HIV/HTLV-1 coinfection. The patient also suffered from multiple squamous cell carcinomas of the scalp, face, lip, and ears, suggesting an UV carcinogenesis of MCC. The purpose of this case report is to emphasize the relationship between immunosuppression (HIV/HTLV-1 coinfection, chronic sun exposure, ocular-cutaneous albinism, pregnancy) and MCC. It highlights the importance of early diagnosis, dermatological screening with a risk-stratified surveillance, particularly in immunosuppressed albino patients in sub-Saharan Africa, and multidisciplinary management of this biologically unique cutaneous cancer.
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