Multicentric reticulohistiocytosis. Electron microscopic and ultracytochemical studies

Abstract

Lesions from a patient affected with multicentric reticulohistiocytosis (MR) were studied by ultracytochemical techniques to determine the relationship of PAS-positive materials and/or acid phosphatase (AP) activity to electron-dense granules found in the large mononucleated or multinucleated giant cells that are characteristic of this entity. The lead phosphate reaction products that mark the sites of AP activity were found in the electron-dense granules. The granules were also PAS positive by the periodic acid-thiosemicarbazide-silver proteinate method. These findings suggest that the PAS-positive and diastase-resistant materials in the large mononucleated or multinucleated giant cells of MR are not phagocytized materials but are pre-existing lysosomes.

Multicentric Reticulohistiocytosis

“…It also has been said [5] that the close relation of cells to small blood vessels suggests that these cells may be actively transferring lipids to and/or from the blood. The studies of Tani et al [ 15] and our own studies did not reveal lipid vac uoles within the tumor cells as other authors have found [5,9,14], Instead we confirmed the existence of electron-dense granules re cently described [15], These granules were PAS-positive and recently described [15], These granules were PAS-positive and showed acid phosphatase activity suggesting that they were no phagocytized material but preexisting lysosomes surrounding a locally degenerative cellular cytoplasm. Thus, it is unclear if lipid accumulation plays a major role in the pathogenesis of MR and it may merely represent a degenerative process in the cells [14], Our case, as the case of Goltz and Laymon [11], showed evidence of a great capillary formation.…”

“…Most of the granules were ovoid and mainly locat ed in the juxta-Golgi areas. They showed an electron-lucid rim between their unit mem brane and matrix, as observed by Tani et al [15], Within the cytoplasm there were 1-10 nuclei, dilated mitochondrias, voluminous Golgi apparatus and well-developed rough endoplasmic reticulum. Desmosomal struc tures were not observed but there were many cytoplasmic processes assembled in laby rinth-like fashion partly forming a membra nous complex ( fig.…”

Multicentric reticulohistiocytosis

“…Autophagic vacuoles surrounded by one or two limiting membranes were also noted. Langerhans’ granules could not be found 57 …”

Multicentric reticulohistiocytosis: Case report with immunohistochemical analysis and literature review

“…Histologic analysis of cutaneous and synovial lesions reveals multinucleated foreign body-type giant cells and smaller histiocytes. The presence of lysosomes and the giant cell's ability to phagocytose have led many to suspect a monocyte/macrophage origin of the multicentric reticulohistiocytosis cells (1)(2)(3). More recently, immunohistochemical studies have yielded conflicting find-ings, with some supporting either a lymphocyte or dermal dendrocyte origin and others still reporting a monocyte/macrophage origin (2)(3)(4)(5)(6)(7).…”