Rickettsia honei Infection in a Traveler Returning From India.

We report a case of Rickettsia honei infection in a US tourist returning from India and the Himalayas. This case highlights a need for awareness of various Rickettsia species endemic to India and the importance for physicians to consider rickettsial diseases in returning travelers with eschar or rash-associated febrile illnesses.

Histiocytic sarcoma with secondary involvement of the skin and expression of CD1a: evidence of indeterminate cell differentiation?

BACKGROUND: Histiocytic sarcoma is an exceedingly rare malignant neoplasm composed of cells with a monocyte/macrophage phenotype. In the current nosology of histiocytic neoplasms, histiocytic sarcoma is separate from indeterminate cell histiocytosis, a generally benign disorder characterized by proliferation of a CD1a+ and S-100+ population of cells lacking Birbeck granules usually limited to the skin. METHODS: We present a case of histiocytic sarcoma in a 64-year-old man presenting as a peritonsillar mass and secondarily involving the skin. RESULTS: The malignant cells in the extracutaneous foci of disease expressed macrophage-associated antigens including S-100 but were CD1a-. The malignant cells in the skin coexpressed CD1a and S-100 but lacked ultrastructural features of Langerhans cells, findings indicative of indeterminate cells. CONCLUSIONS: We discuss the clinical and histopathologic differential diagnosis in association with prior reported cases of histiocytic sarcoma, particularly in cases involving the skin and cases expressing the Langerhans cell-associated antigen CD1a.

Cutaneous Rosai-Dorfman disease: comprehensive review of cases reported in the medical literature since 1990 and presentation of an illustrative case.

BACKGROUND: The latest comprehensive review of primary cutaneous Rosai-Dorfman disease was published as part of an exhaustive survey of sinus histiocytosis with massive lymphadenopathy in 1990. Since then, much progress has been made in the understanding of malignant lymphoma and benign disorders of lymphoid and histiocytic origin. OBJECTIVE: We reviewed cases of primary cutaneous Rosai-Dorfman disease published since 1990 and discuss their clinical and pathologic features, comparing them with cases of systemic Rosai-Dorfman disease. METHODS: We conducted a search of the National Library of Medicine PubMed database for cases of cutaneous Rosai-Dorfman disease reported in the English-language medical literature since February 1990. RESULTS: We identified 72 patients with cutaneous Rosai-Dorfman (female to male ratio 1:0.5). The gross appearance and number or distribution of lesions were highly variable. Abnormal laboratory data included peripheral blood cytopenias (10 patients) and increased gammaglobulin fraction (10 patients). The response to treatment was variable. CONCLUSION: Purely cutaneous disease without the characteristic lymphadenopathy is rare but has been increasingly reported in the literature. Compared with patients with systemic Rosai-Dorfman disease, patients with primary cutaneous Rosai-Dorfman disease are older, women are more commonly affected, and whites are more likely than blacks to be afflicted.

A patient with extensive stem cell factor-induced hyperpigmentation.

Stem cell factor (SCF) is a cytokine that stimulates development of erythroid precursors and, consequently, may have potential importance in the treatment of certain anemias. We report a case of a young woman with Diamond-Blackfan anemia who received SCF treatment. One effect of SCF treatment is cutaneous hyperpigmentation at the injection site. In contrast to previously reported cases of patients who had fewer SCF injections, her hyperpigmentation was extensive and of major cosmetic concern. SCF may play a role in a number of disease processes. This case demonstrates the need to consider the potential pigmentary side effects of SCF therapy and to make careful selection of the injection sites.