Antemortem cytologic diagnosis of pulmonary Langerhans cell histiocytosis in a cat.

Feline pulmonary Langerhans cell histiocytosis (FPLCH) is a rare histiocytic proliferative disease of middle-aged to older domestic cats. Langerhans cells in the terminal airways proliferate and infiltrate the interstitium and the airways to a lesser degree, widely effacing normal parenchyma. Historically, definitive diagnosis has required postmortem evaluation where pulmonary lesions have a classic gross and histologic morphology. Here, we present the first documented antemortem diagnosis of FPLCH using bronchoalveolar lavage (BAL) cytology and immunocytochemistry (ICC) in a 9-year-old British shorthair mix. The cat had a 3-month history of respiratory difficulty that was refractory to steroids and antimicrobials. Pulmonary radiographs had marked diffuse changes with a complex bronchointerstitial and micronodular pattern. BAL cytology revealed neutrophilic inflammation and markedly increased histiocytes with morphology distinct from typical pulmonary macrophages. ICC characterized histiocytes as CD1a+ /E-cadherin+ /CD11b- /PanCK- , consistent with a Langerhans cell phenotype. The cat was humanely euthanized due to poor prognosis and presented for necropsy. Gross, histopathologic, immunophenotypic, and ultrastructural findings confirmed a diagnosis of FPLCH. Proliferative cells were E-cadherin+ /Iba-1+ /CD18+ /CD1a+ /CD5+ /MHCII+ /CD204- /CD4- ; transmission electron microscopy identified the presence of Birbeck granules in the proliferating histiocytes, consistent with previous reports of FPLCH.

[Trident sign in spinal cord neurosarcoidosis]. / Signo del tridente en la neurosarcoidosis medular.

TITLE: Signo del tridente en la neurosarcoidosis medular.

M2 Macrophages in Crystal Storing Histiocytosis Associated with Plasma Cell Myeloma.

Crystal Storing Histiocytosis (CSH) is a rare entity occurring in association with underlying lymphoproliferative disorders and plasma cell neoplasms. It denotes accumulation of immunoglobulin crystals in the histiocyte cytoplasm. In this study, we report a patient with plasma cell myeloma who presented with bilateral comminuted femur fractures. Histological examination of fracture tissue revealed hypercellular (~100%) marrow with extensive involvement by sheets of histiocytes with abundant eosinophilic cytoplasm admixed with scattered plasma cells. Intracytoplasmic diamond and rhomboid crystals within histiocytes were demonstrated by electron microscopy. Immunohistochemistry highlighted monotypic plasma cells with kappa restriction, representing 20-30% of marrow cellularity; however, non-polarizable cytoplasmic striations in histiocytes were negative for light chain expression. A diagnosis of crystal-storing histiocytosis associated with plasma cell myeloma was rendered. Further evaluation of these macrophages is positive for CD163 and COX2 and shows pSTAT3 with variable nuclear staining in some histiocytes. This case demonstrates that numerous M2 macrophages are present as crystal storing histiocytosis; and this knowledge might convey prognostic and therapeutic significance for the patients with crystal storing histiocytosis.

Lesiones cutáneas de muy larga evolución / Very long evolution skin injuries

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Scanning electron microscopy of granuloma annulare

Abstract: Light microscopy of granuloma annulare shows mucin deposition with lympho-histiocytic infiltrate. We describe the ultrastructural three-dimensional aspects of a typical case of granuloma with characteristic histopathological findings. At the ultrastructural level, affected collagen bundles and granular mucin deposition were observed. Round cells corresponding to lymphocytes were identified. Bigger oval cells, corresponding to isolated or palisading histiocytes were also found. The ultrastructural aspects overlap with light microscopy and contribute to its iconographic documentation.

Scanning electron microscopy of granuloma annulare.

Light microscopy of granuloma annulare shows mucin deposition with lympho-histiocytic infiltrate. We describe the ultrastructural three-dimensional aspects of a typical case of granuloma with characteristic histopathological findings. At the ultrastructural level, affected collagen bundles and granular mucin deposition were observed. Round cells corresponding to lymphocytes were identified. Bigger oval cells, corresponding to isolated or palisading histiocytes were also found. The ultrastructural aspects overlap with light microscopy and contribute to its iconographic documentation.

Gastric lanthanosis (lanthanum deposition) in dialysis patients treated with lanthanum carbonate.

Lanthanum carbonate (LaC) is used to prevent hyperphosphatemia in dialysis patients. It is commonly believed that there is little LaC absorption from the intestines. However, La deposition in the gastric mucosa, which we coined "gastric lanthanosis", was recently reported. We describe here the clinicopathological features of and a possible mechanism for gastric lanthanosis. This study included 23 patients with definite gastric lanthanosis. We extracted characteristic clinicopathological features of gastric lanthanosis by computed tomography (CT) imaging and endoscopic, histologic, electron-microscopic, and element analysis examinations. The Helicobacter pylori infection rate in the lanthanosis group was much lower than that among the general population. The clinicopathological features characteristic of gastric lanthanosis were mucosal high-density linear appearance by CT, reflective bright-white spots (BWS) by gastroscopy, eosinophilic histiocytes occasionally phagocytizing foreign materials by histology, and numerous electron-dense particles in the histiocytes. The particles had burr-like skeletons resembling La crystals. Gastric lanthanosis is an under-reported, but not a rare lesion. It is characterized by endoscopic BWS and histologic eosinophilic histiocytes in dialysis patients treated with LaC. The proposed mechanism for gastric lanthanosis is that LaC is dissolved by gastric juice, crystallized within the mucosa and is phagocytized by histiocytes.

Localized pulmonary crystal-storing histiocytosis complicating pulmonary mucosa-associated lymphoid tissue lymphoma presenting with multiple mass lesions.

Crystal-storing histiocytosis (CSH) is an uncommon finding in lymphoplasmacytic disorders that presents histiocytes with abnormal intralysosomal accumulations of immunoglobulin light chains as crystals of unknown etiology. A 38-year-old woman with antiphospholipid syndrome had a surgical lung biopsy because of multiple lung mass lesions. In a right middle lobe lesion, lymphoplasmacytic cells had a monocytoid appearance, destructive lymphoepithelial lesions, and positive immunoglobulin heavy chain (IGH) gene rearrangements. A right upper lobe lesion manifested proliferating rounded histiocytes with abundant, deeply eosinophilic cytoplasm and negative IGH gene rearrangements. Electron microscopy and mass spectrometry revealed a case of pulmonary CSH: abnormal proliferation of the immunoglobulin κ chain of a variable region that may be crystallized within plasma cells and histiocytes. We report a rare case of localized pulmonary CSH complicating pulmonary mucosa-associated lymphoid tissue lymphoma with multiple mass lesions. We demonstrate advances in the understanding of the pathogenesis of CSH by various analyses of these lesions.

Birbeck granules, worm-like bodies and "lupus erythematosus virus".

The origin of worm-like bodies and their relationship with Birbeck granules is poorly understood. To clarify the origin of worm-like bodies and their relationship with Birbeck granules. Over 800 electron micrographs of histiocytic disorders and several appendage tumours were reviewed in order to check for worm-like bodies and Birbeck granules. Worm-like bodies were most often encountered in mildly- to moderately-proliferative histiocytic tumours. Birbeck granules were observed in more malignant conditions. Narrow endoplasmic reticulum (Nrer), which resembles worm-like bodies, was abundant in worm-like body-rich cells and coexisted with Birbeck rods. Nrer is thought to be one of the candidates that gives rise to worm-like bodies. An ultrastructural similarity exists between worm-like bodies (and octopus body formation) and the so-called "lupus erythematosus virus". The presence of Nrer is often concomitant with other organelle markers, and could be a candidate for the origin of worm-like bodies.

Passage-dependent morphological and phenotypical changes of a canine histiocytic sarcoma cell line (DH82 cells).

DH82 cells represent a permanent macrophage cell line isolated from a dog with histiocytic sarcoma (HS) and are commonly used in various fields of research upon infection and cancer, respectively. Despite its frequent use, data on cell surface antigen expression of this cell line are fragmentary and in part inconsistent. We therefore aimed at a detailed morphological and antigenic characterization of DH82 cells with respect to passage-dependent differences. Cellular morphology of early (≤ 13) and late (≥ 66) passages of DH82 cells was evaluated via scanning electron microscopy. Moreover, cells were labelled with 10 monoclonal antibodies directed against CD11c, CD14, CD18, CD44, CD45, CD80, CD86, MHC-I, MHC-II, and ICAM-1 for flow cytometric analysis. Early passage cells were characterized by round cell bodies with abundant small cytoplasmic projections whereas later passages exhibited a spindle-shaped morphology with large processes. The percentage of CD11c-, CD14-, CD18-, CD45-, and CD80 positive cells significantly decreased in late passages whereas the expression of CD44, CD86, MHC-I, MHC-II and ICAM-1 remained unchanged. DH82 cells represent a remarkably heterogeneous cell line with divergent antigenic and morphologic properties. The present findings have important implications for future studies, which should consider distinct characteristics with regard to the used passage.