Shiitake dermatitis: a report of 3 cases and review of the literature.

Shiitake mushroom-induced toxicoderma, or shiitake dermatitis, is a widely recognized phenomenon in Japan, China, and Korea but only recently has been reported outside of Asia. Affected individuals develop a characteristic pattern of whiplike, linear, erythematous wheals within 1 to 2 days after consumption of raw or cooked shiitake mushrooms. Lentinan, a polysaccharide component of shiitake mushrooms with antitumor properties, is thought to instigate a toxic reaction, resulting in the appearance of a rash. Shiitake dermatitis is self-limited and typically resolves within days to weeks of its appearance.

Equestrian perniosis: a report of 2 cases and a review of the literature.

Equestrian perniosis (EP) is a rare condition in which patients develop tender burning nodular plaques on their bilateral thighs after riding in the cold. These lesions tend to resolve rapidly with minimal exposure to cold, and wearing loose, layered warm clothing. Unlike acral perniosis, EP has no known systemic disease associations, although 2 reported cases did have elevated cold agglutinins. The histology of this disease is similar to perniosis; however, EP is distinct in that the perivascular lymphocytic infiltrate prominently involves the fat. In this case report, we discuss the clinical and histological findings in 2 cases of EP, including the first documented in a man.

Mycobacterial infection identified with broad-range PCR amplification and suspension array identification.

The case of a 66-year-old female who developed sudden redness and swelling of her left thumb is presented. A biopsy showed well formed granulomas, mixed inflammation with a predominance of neutrophils, and acid-fast bacilli. After negative culture results, tissue was sent for a broad-range polymerase chain reaction amplification followed by suspension array identification, which classified the pathogenic organism as Mycobacterium avium-intracellulare. The patient was started on clarithromycin, rifabutin and ethambutol leading to clinical improvement. M. avium-intracellulare is present in soil, fresh water, sea water, dairy products and some animal tissues. Primary cutaneous manifestations are uncommon in the immunocompetent host. As cultures may be negative or can take up to three weeks to show growth, the molecular approach described here offers an opportunity for more rapid and specific diagnosis.

Cutaneous adverse reaction to infliximab: report of psoriasis developing in 3 patients.

Infliximab is a chimeric immunoglobulin G1kappa monoclonal antibody against tumor necrosis factor alpha (TNF-alpha), a proinflammatory cytokine that participates in both normal immune function and the pathogenesis of many autoimmune disorders. Treatment with infliximab reduces the biologic activities of TNF-alpha and thus is indicated in the treatment of rheumatoid arthritis, Crohn disease, ankylosing spondylitis, psoriatic arthritis, plaque psoriasis, and ulcerative colitis. To our knowledge, there have been 13 case reports of new-onset psoriasis, psoriasiform dermatitis, and palmoplantar pustular psoriasis that developed during treatment with infliximab. We report 3 additional cases of biopsy-proven new-onset psoriasis that developed while the patients underwent treatment with infliximab for inflammatory bowel disease. Although the mechanism for the development of psoriasis in these patients is unclear, several possible explanations are proposed. With increasing use of infliximab and other TNF-alpha inhibitors in clinical practice, more cases of similar reactions to these drugs probably will be reported and are necessary to determine the importance of this eruption.

Methotrexate-associated lymphoproliferative disorder in a patient with rheumatoid arthritis presenting in the skin.

A 91-year-old woman who had been taking methotrexate for approximately 5 years for rheumatoid arthritis developed papules and nodules on her face that enlarged during 6 months. A series of biopsy specimens demonstrated a lymphoplasmacytic infiltrate with increasingly atypical histopathologic features that resembled diffuse large B-cell lymphoma. Epstein-Barr virus was not identified. Withdrawal of methotrexate resulted in complete resolution of all lesions within 8 weeks. This case illustrates the rare occurrence of methotrexate-associated lymphoproliferative disorder with primary presentation in the skin and documents clinical and histopathologic progression from early changes to fully developed lesions.