Histiocytosis x: light and electron microscopic study with special reference to skin manifestations

A total of 25 cases of histiocytic infiltration of the skin were studied. These comprised 15 patients diagnosed as having histiocytosis X [12 cases of eosinophilic granuloma, one case of Hand- Schueller-Christian disease and two cases of letterer Siwe disease] and 10 cases of non-X histiocytic lesions of the skin and subcutaneous tissues [two cases of xanthogranuloma and eight fibrous histiocytomas]. The various cutaneous lesions encountered were described. The diagnostic histopathologic features of each group were presented. Langerhans cells with folded, indented or lobulated nuclei were identified in all the 15 cases of histiocytosis X. Langerhans granules, trilaminar membranous loops and comma shaped bodies were found in 20-50% of cells of all the five cases of histiocytosis X examined ultrastructurally irrespective to the clinical form of the disease. The importance of electron microscopy as a diagnostic tool for confirmation of the diagnosis and differentiating those cutaneous lesions due to histiocytosis X from non-X histiocytic tumors is emphasized

Kaposi's sarcoma: ultrastructural study and immunoperoxidase localization of factor VIII-related antigen

Fifteen patients with Kaposi's sarcoma were studied. Nine patients had early cutaneous plaques and six patients had locally extensive nodular lesions with lymph node affection in two patients. Satisfactory electron micrographs after initial 10% formalin fixation were obtained in two cases. Factor VIII-related antigen localization was studied by immunoperoxidase stain in eight cases with available paraffin blocks. Ultrastructurally, the tumor contained variable mixture of cells including endothelial cells, pericytes, fibroblasts and myofibroblasts. Immunoperoxidase staining for factor VIII-related antigen was positive in all the eight cases with positive cytoplasmic staining in the endothelial cells lining of the well formed blood vessels and some proliferating spindle cells indicating their vascular [endothelial] derivation. The histologic features which help in the diagnosis of Kaposi's sarcoma from other histologic entities were reviewed. The presence of abnormally shaped vessels with jagged outline was the most helpful single criterion to diagnose early lesions