Urticating histiocytosis: a mast cell-rich variant of histiocytosis X

Langerhans cell histiocytosis: A great imitator

Langerhans cell histiocytosis (LCH) is an uncommon but serious inflammatory neoplasia that affects many organs, including the skin. Though uncommon, it should remain high on a clinician's differential diagnosis in treatment-resistant cases of conditions, such as seborrheic dermatitis, diaper dermatitis, arthropod bites, and many more. A thorough history nd physical examination for each patient can aid in the diagnosis; however, if clinically suspicious for LCH, a punch biopsy should be performed. Histologic evaluation of LCH is often enough to differentiate it from the many clinical mimickers. Characteristic findings include a histiocytic infiltrate with "coffee bean"-cleaved nuclei, rounded shape, and eosinophilic cytoplasm. Immunohistochemical stains, including CD1a, S100, and CD207 (langerin) are often needed for a definitive diagnosis. Electron microscopy also demonstrates the ultrastructural presence of Birbeck granules, but this is no longer needed due to immunohistochemical staining. Treatment is often necessary for LCH, if systemic involvement exists.

A case of cutaneous mastocytosis in a child with prominent Langerhans cell infiltration

We recently encountered a 2-year-old boy with slightly infiltrative brown papules on the face, trunk, and extremities. Stroking of one of the papules produced an urticarial wheal (positive Darier's sign). Histopathologic tests revealed a dense infiltration of mast cells containing numerous granules and showing metachromasia under Toluidine blue staining. Immunohistochemical tests revealed that these cells were positive for CD68 and for c-kit. In addition, dermal dendritic cells that were positive for S100 and CD1a immunostaining were intermingled with the mast cells. We confirmed through electron microscopy that the dermal dendritic cells that were observed adjacent to the infiltration of mast cells had Birbeck granules in their cytoplasm, namely Langerhans cells. However, because of the greater numbers of mast cells than Langerhans cells, and because of the absence of both monomorphic LC proliferation and systemic symptoms of Langerhans cell histiocytosis, the present case favors a diagnosis of cutaneous mastocytosis in a child with Langerhans cell infiltration.

Urticating Hashimoto-Pritzker Langerhans cell histiocytosis

Red-brown papules developing during the neonatal period may present a diagnostic dilemma. The Darier sign has been a reliable feature in the diagnosis of mastocytosis. However, the cutaneous infiltrate of Hashimoto-Pritzker Langerhans cell histiocytosis (LCH) may contain a large number of mast cells, leading to confusion both clinically and histologically. We report an infant who developed red-brown papules of Hashimoto-Pritzker LCH during the neonatal period and presented with a positive Darier sign and acute urticaria.

Immunohistochemical and ultrastructural study of histiocytosis X and non-X histiocytoses

The diagnostic reliability of ultrastructural and immunohistochemical examinations on routinely processed biopsy specimens of cutaneous histiocytic proliferations (histiocytosis X, n = 7; juvenile xanthogranuloma, n = 4; necrobiotic xanthogranuloma, n = 2; traumatic granuloma of the tongue, n = 1) was evaluated. S-100 protein, peanut agglutinin, and the antibody Mac-387 were used as markers for histiocytes. The frequency of Birbeck granule-containing cells in seven histiocytosis X lesions did not correspond with the number of S-100+ or peanut agglutinin+ cells. All neoplastic histiocytosis X cells were positive for S-100 protein and peanut agglutinin but were negative for Mac-387. Histiocytes of juvenile xanthogranuloma, necrobiotic xanthogranuloma, and traumatic granuloma were strongly positive for Mac-387 but were negative for S-100 protein and peanut agglutinin, except for the peanut agglutinin-reactive Touton giant cells. Mac-387 reliably differentiates histiocytic proliferations of the monocyte/macrophage system from those of the dendritic cell system. For the diagnosis of histiocytosis X, both S-100 protein and peanut agglutinin positivity in histiocytes is as reliable as ultrastructural demonstration of Birbeck granules.

Adult mastocytosis: an immunophenotypic and flow-cytometric investigation

Skin mast cells of five patients with mastocytosis/urticaria pigmentosa and from four normal controls were immunophenotyped with a panel of 17 monoclonal antibodies; peripheral blood mononuclear cells from the patients were similarly labelled and analysed by flow cytometry. Cutaneous mast cells expressed leucocyte common antigen and markers of macrophage/monocyte lineage suggesting a common progenitor in the ontogeny of the two cell types. The mast cells from the patients differed from the controls, expressing HLA-DR in four cases, and this may be a feature of proliferating cells. The patients' peripheral blood T lymphocytes showed a marked increase in the activation markers HLA-DR and CD25 suggesting a contributory role, possibly via cytokines, in driving mast-cell proliferation.

Letterer-Siwe disease in adults

Histiocytosis X (HX) is a rare disorder of histiocytic proliferation characterized by a broad spectrum of clinicopathologic disease. An unusual case of Letterer-Siwe disease (LSD) or subacute disseminated HX in a 71-year-old woman is presented. The patient had a 3-year history of splenomegaly before skin lesions developed. She presented to our clinic at 1.5 years later and the diagnosis of HX was made by skin biopsy. Topical nitrogen mustard (NM) therapy resulted in complete clearing of cutaneous lesions. Her condition was stable over the next 10 months. However, she subsequently suffered a rapid and fatal dissemination of her disease. Systemic treatment with prednisone, vinblastine sulphate, and suppressin A (SA) (a calf thymus derived hormone preparation that specifically induces suppressor T-cells) was ineffective. Characteristic histopathologic, immunohistochemical, and electron microscopic findings of HX are illustrated. A review of the adult cases of LSD and treatment options for HX are presented and discussed.