Leukemia cutis in acute myeloid leukemia signifies a poor prognosis.

Leukemia cutis (LC) is a rare neoplastic infiltration of the skin or subcutaneous tissue by leukemic cells. Because it correlates with sites of additional extramedullary involvement, it typically portends a poor prognosis. Although most cases of LC present concurrently with bone marrow infiltration, skin findings may precede systemic involvement in some cases; thus, early detection by dermatologists is essential. We report a case of a 66-year-old man who was diagnosed with acute myeloid leukemia (AML) based on the cutaneous presentation of LC.

Langerhans cell histiocytosis in children: History, classification, pathobiology, clinical manifestations, and prognosis.

Langerhans cell histiocytosis (LCH) is an inflammatory neoplasia of myeloid precursor cells driven by mutations in the mitogen-activated protein kinase pathway. When disease involves the skin, LCH most commonly presents as a seborrheic dermatitis or eczematous eruption on the scalp and trunk. Evaluation for involvement of other organ systems is essential, because 9 of 10 patients presenting with cutaneous disease also have multisystem involvement. Clinical manifestations range from isolated disease with spontaneous resolution to life-threatening multisystem disease. Prognosis depends on involvement of risk organs (liver, spleen, and bone marrow) at diagnosis, particularly on presence of organ dysfunction, and response to initial therapy. Systemic treatment incorporating steroids and cytostatic drugs for at least one year has improved prognosis of multisystem LCH and represents the current standard of care.

Langerhans cell histiocytosis in children: Diagnosis, differential diagnosis, treatment, sequelae, and standardized follow-up.

A definitive diagnosis of Langerhans cell histiocytosis (LCH) requires a combination of clinical presentation, histology, and immunohistochemistry. The inflammatory infiltrate contains various proportions of LCH cells, the disease hallmark, which are round and have characteristic "coffee-bean" cleaved nuclei and eosinophilic cytoplasm. Positive immunohistochemistry staining for CD1a and CD207 (langerin) are required for a definitive diagnosis. Isolated cutaneous disease should only be treated when symptomatic, because spontaneous resolution is common. Topical steroids are first-line treatment for localized disease of skin and bone. For multifocal single-system or multisystem disease, systemic treatment with steroids and vinblastine for 12 months is the standard first-line regimen. Current research is seeking more effective regimens because recurrence rates, which increase the risk of sequelae, are still high (30-50%) in patients with multisystem disease. An active area of research is the use of targeted therapy directed at the mitogen-activated protein kinase pathway. Adequate follow-up to monitor for disease progression, relapse, and sequelae is recommended in all patients.

Complete Resolution of Mycobacterium marinum Infection with Clarithromycin and Ethambutol: A Case Report and a Review of the Literature.

A 70-year-old, immunocompetent male presented with mildly painful and pruritic erythematous patches and vesicles on the right dorsal aspect of the distal middle finger present for four weeks. Other skin lesions or systemic symptoms were notably absent. The patient failed to respond to valacyclovir, topical triamcinolone acetonide ointment, trimethoprim-sulfamethoxazole, and cephalexin for presumptive diagnoses of recurrent herpetic whitlow, dyshidrotic eczema, and blistering distal dactylitis, respectively. Furthermore, biopsy findings were inconsistent with eczema, psoriasis, or viral or fungal infection as potential etiologies. Mycobacterium marinum infection was then considered due to the patient's observation that the lesion appeared three weeks after purchasing a home fish tank. Mycobacterium marinum, referred to as "fish tank granuloma" as a result of its typical association with aquarium exposure, is usually diagnosed clinically and treated empirically due to the organism's slow-growing nature. In light of the infection's low prevalence, large studies regarding treatment options are limited. Our patient's lesion resolved within two weeks of treatment with clarithromycin (500mg twice a day) and ethambutol (15mg/kg once a day), which was then continued for two more months. Prior to this treatment, the patient's lesion had cleared completely with minocycline; we attribute recurrence to not continuing therapy past lesion resolution.