Porphyria cutanea tarda: an intriguing genetic disease and marker.

Porphyrias are a group of intriguing genetic diseases of the heme pathway, of which porphyria cutanea tarda (PCT) is the most common. Resulting from a defect in enzymes in the porphyria pathway, PCT has been linked to several conditions. Recent studies have demonstrated a change in thinking regarding the human immunodeficiency virus (HIV) and development of PCT. The exacerbation of PCT with contraction of HIV is now believed to result from coinfection from the hepatitis C virus (HCV). Blistering of sun-exposed skin, a classic presenting sign of PCT, is not exclusive to the condition. Cutaneous findings must also trigger physicians to consider additional types of porphyrias, such as variegate porphyria. The diagnosis of pseudoporphyria, which does not result from enzymatic absence, must be considered in patients with photosensitivity and cutaneous bullae. Recent health food trends, such as chlorophyll, have been linked to pseudoporphyria. PCT is a serious condition in which accurate diagnosis is necessary for appropriate management.

Chikungunya fever: an emerging viral infection threatening North America and Europe.

Since the beginning of the twenty-first century, there has been a rapid rise in the number of cases of chikungunya. Initially limited to islands of the southwestern Indian Ocean, the virus has spread across Africa and into the islands of the Caribbean. Cutaneous symptoms include a morbilliform eruption, hyperpigmented macules, and aphthae-like ulcers. Patients often also experience fever and joint pain. We review the methods for diagnosis, treatment, and prevention of this increasingly prevalent virus now emerging more commonly in Europe and North America.

Shiitake Mushroom Dermatitis: A Review.

Shiitake mushroom dermatitis is a cutaneous reaction caused by the consumption of raw or undercooked shiitake mushrooms. Symptoms include linear erythematous eruptions with papules, papulovesicles or plaques, and severe pruritus. It is likely caused by lentinan, a heat-inactivated beta-glucan polysaccharide. Cases were initially reported in Japan but have now been documented in other Asian countries, North America, South America, and Europe, as this mushroom is now cultivated and consumed worldwide. Shiitake mushroom dermatitis may result from mushroom ingestion or from handling, which can result in an allergic contact dermatitis.