ALK-positive histiocytosis: an expanded clinicopathologic spectrum and frequent presence of KIF5B-ALK fusion.

In 2008, we presented three cases of ALK-positive histiocytosis as a novel systemic histiocytic proliferation of early infancy with hepatosplenomegaly and dramatic hematological disturbances. This series of 10 cases (including the original three cases) describes an expanded clinicopathological spectrum and the molecular findings of this histiocytic proliferation. Six patients had disseminated disease: five presented in early infancy with eventual disease resolution, and the sixth presented at 2 years of age and died of intestinal, bone marrow, and brain involvement. The other four patients had localized disease involving nasal skin, foot, breast, and intracranial cavernous sinus - the first three had no recurrence after surgical resection, while the cavernous sinus lesion showed complete resolution with crizotinib therapy. The lesional histiocytes were very large, with irregularly folded nuclei, fine chromatin, and abundant eosinophilic cytoplasm, sometimes with emperipolesis. There could be an increase in foamy histiocytes and Touton giant cells with time, resembling juvenile xanthogranuloma. Immunostaining showed that the histiocytes were positive for ALK, histiocytic markers (CD68, CD163) and variably S100, while being negative for CD1a, CD207, and BRAF-V600E. Next-generation sequencing-based anchored multiplex PCR (Archer® FusionPlex®) performed in six cases identified KIF5B-ALK gene fusion in five and COL1A2-ALK fusion in one. There was no correlation of gene fusion type with disease localization or dissemination. The clinicopathological spectrum of ALK-positive histiocytosis is broader than originally described, and this entity is characterized by frequent presence of KIF5B-ALK gene fusion. We recommend that every unusual histiocytic proliferative disorder, especially disseminated lesions, be tested for ALK expression because of the potential efficacy of ALK inhibitor therapy in unresectable or disseminated disease.

Atrophying pityriasis versicolor as an idiosyncratic T cell-mediated response to Malassezia: A case series.

BACKGROUND: Atrophying pityriasis versicolor (PV), first described in 1971, is a rare variant in which lesions appear atrophic. OBJECTIVE: We sought to determine the pathophysiology of atrophying PV. METHODS: A retrospective chart review identified 6 cases of atrophying PV. In all cases, routine light microscopy, an elastic tissue stain, and immunohistochemical assessment for the expression of CD3, CD4, CD8, GATA3 and CXCR3 was performed. RESULTS: All cases demonstrated hyperkeratosis with intracorneal infiltration by pathogenic hyphal forms as well as epidermal attenuation and papillary dermal elastolysis. A supervening, mild-to-moderate, superficial lymphocytic infiltrate was noted and characterized by a focal CD8+ T cell-mediated interface dermatitis along with a mixed T-cell infiltrate composed of GATA3+ and CXCR3+ T cells. LIMITATIONS: Small sample size and the loss of some patients to follow-up. CONCLUSION: Atrophying PV represents the sequelae of a mixed helper T-cell (TH1 and TH2) idiosyncratic immune response to Malassezia and can present as a protracted dermatosis that may clinically mimic an atypical lymphocytic infiltrate. TH1 cytokines can recruit histiocytes, a source of elastases, and upregulate matrix metalloproteinase activity, which may contribute to epidermal atrophy.

Disseminated histiocytoses biomarkers beyond BRAFV600E: frequent expression of PD-L1.

The histiocytoses are rare tumors characterized by the primary accumulation and tissue infiltration of histiocytes and dendritic cells. Identification of the activating BRAFV600E mutation in Erdheim-Chester disease (ECD) and Langerhans cell histiocytosis (LCH) cases provided the basis for the treatment with BRAF and/or MEK inhibitors, but additional treatment options are needed. Twenty-four cases of neoplastic histiocytic diseases [11 extrapulmonary LCH, 4 ECD, 4 extranodal Rosai-Dorfman disease (RDD), 3 follicular dendritic cell sarcoma (FDCS), 1 histiocytic sarcoma (HS) and 1 blastic plasmacytoid dendritic cell neoplasm (BPDCN)] were analyzed using immunohistochemical and mutational analysis in search of biomarkers for targeted therapy. BRAF V600E mutations were detected in 4/11 LCH and 4/4 ECD cases. A pathogenic PTEN gene mutation and loss of PTEN protein expression were identified in the case of HS. Increased expression of PD-L1 (≥2+/≥5%) was seen in 3/4 ECD, 7/8 LCH, 3/3 FDCS and 1/1 HS, with overall 81% concordance between 2 antibodies used in the study (SP142 vs. MAB1561 clone). These results show for the first time significant expression of the PD-L1 immune checkpoint protein in these disorders, which may provide rationale for addition of immune check-point inhibitors in treatment of disseminated and/or refractory histiocytoses.

Cutting needle biopsy combined with immunohistochemical study of myeloperoxidase for the diagnosis of histiocytic necrotizing lymphadenitis.

CONCLUSION: Cutting needle biopsy (CNB) combined with immunohistochemical study of myeloperoxidase (MPO) is a useful minimally invasive diagnostic procedure for histiocytic necrotizing lymphadenitis (HNL). OBJECTIVES: HNL is mainly diagnosed by pathological findings of open surgical biopsy (OSB) specimens. Recently the appearance of anti-MPO positive histiocytes has been reported as a highly specific pathological diagnosis for HNL. Considering the cosmetic impact and burden on the patients, we performed CNB combined with immunohistochemical study of MPO for the diagnosis of HNL. Few studies have reported the utility of this method in the diagnosis of HNL. METHODS: A retrospective study was conducted using clinical data from 20 HNL patients. RESULTS: CNB was performed in 8 patients and OSB in 13 (OSB after CNB in 1). MPO-positive histiocytes were observed in all of the 20 cases. The accuracy of the diagnoses was finally confirmed by the clinical courses in all cases.

The role of iNOS inhibitors on lung injury induced by gastrointestinal decontamination agents aspiration.

Aspiration is a devastating complication during decontamination procedure in poisoning patients. We have investigated whether S-methylisothiourea protects different pulmonary aspiration gastrointestinal decontamination agent-induced lung injury in rats. Forty-two male Sprague-Dawley rats were assigned to one of six groups (n = 7): normal saline, activated charcoal, polyethylene glycol, normal saline + S-methylisothiourea treated activated charcoal + S-methylisothiourea treated and polyethylene glycol + S-methylisothiourea treated. Normal saline, activated aharcoal and polyethylene glycol were instilled into the lungs. The rats received S-methylisothiourea i.p twice daily for 7 days. Serum surfactant protein D, oxidative stress products and inducible nitric oxide synthase expression in the lung were investigated. The aspiration of activated charcoal significantly increased all histopathological scores (P < 0.01). Only peribronchial inflammatory cell infiltration, alveolar edema, and alveolar histiocytes were increased in the polyethylene glycol groups as compared to the normal saline group (P < 0.05). Pulmonary aspiration increased serum malondialdehyde (P < 0.001), and surfactant protein D (P < 0.05) levels and decreased serum superoxide dismutase levels (P < 0.05). S-methylisothiourea treatment decreased all histopathological scores in the activated charcoal treated S-methylisothiourea group (P < 0.01) and only decreased alveolar edema and alveolar histiocytes in the polyethylene glycol-treated S-methylisothiourea group (P < 0.05). S-methylisothiourea treatment reduced elevated oxidative factors, inducible nitric oxide synthase activity and serum surfactant protein D levels. Our findings showed that S-methylisothiourea may be a protective drug against Activated Charcoal and Polyethylene Glycol-induced lung injury.

Transglutaminases: the missing link in nephrogenic systemic fibrosis.

Nephrogenic systemic fibrosis (NSF), also known as nephrogenic fibrosing dermopathy (NFD), occurs in renal failure patients after gadolinium contrast exposure. The fibrosis of the dermis and subcutaneous septae accompanies fibrosis of other organs, including the heart, liver, lungs, and muscle. The fibrotic skin demonstrates increased dermal collagen, fibroblasts, and mucin. The mechanism by which gadolinium is associated with fibrosis is not known. We tested the hypothesis that upregulation of transglutaminases contributes to the fibrosis seen in the organs, including skin, of renal failure patients exposed to gadolinium contrast. We performed immunohistochemical studies using antibodies to transglutaminase-2, factor XIIIa, transglutaminase isopeptide, and the histiocyte marker CD68 on five archived skin biopsies of NSF. The results indicate that the dermal fibroblasts and histiocytes of NSF express transglutaminase-2, CD68, factor XIIIa, and transglutaminase isopeptide, indicating increased expression and/or activation of transglutaminases in NSF. We recommend further research into the use of transglutaminase inhibitors in the treatment and prevention of NSF.

Pre-exposure to high glucose augments lipopolysaccharide-stimulated matrix metalloproteinase-1 expression by human U937 histiocytes.

BACKGROUND AND OBJECTIVES: It has been well established that patients with diabetes have increased prevalence and severity of periodontal diseases. However, the underlying mechanisms are not well understood. Given that bacterial infection is the primary cause of periodontal disease, we postulated that hyperglycemia may interplay with bacterial virulence factors such as lipopolysaccharide to up-regulate matrix metalloproteinase (MMP), leading to increased periodontal tissue destruction. METHODS AND RESULTS: We showed that prolonged pre-exposure of U937 histiocytes to high glucose markedly increased lipopolysaccharide-stimulated MMP-1 secretion and mRNA expression. Our results also showed that the effect of high glucose on lipopolysaccharide-induced MMP-1 expression is cell type-specific because no similar response was observed in human gingival fibroblasts. In addition to MMP-1, high glucose also augments lipopolysaccharide-stimulated MMP-7, -8, and -9 mRNA expression. In the investigation of the signaling pathways involved in the enhancement of lipopolysaccharide-induced MMP-1 expression by high glucose, we found that both high glucose and lipopolysaccharide regulate MMP-1 expression through the nuclear factor kappaB (NFkappaB) and mitogen-activated protein kinase (MAPK) cascades. CONCLUSIONS: The present study has shown that pre-exposure to high glucose and subsequent lipopolysaccharide treatment synergistically stimulates MMP-1 expression by mononuclear phagocytes through the NFkappaB and MAPK signaling pathways. This study has thus delineated a pathogenic mechanism that may be involved in the exacerbated periodontal disease in diabetic patients.

IFN-gamma pretreatment augments immune complex-induced matrix metalloproteinase-1 expression in U937 histiocytes.

We reported recently that immune complexes (ICs) induced matrix metalloproteinase-1 (MMP-1) expression in U937 histiocytes. The present study was undertaken to determine the effect of pretreatment of U937 cells with interferon-gamma (IFN-gamma) on IC-induced MMP-1 expression. Our flow cytometry studies showed that IFN-gamma upregulated the surface expression of FcgammaRI, but not FcgammaRII. Results also showed that pretreatment of the cells with IFN-gamma augmented LDL-containing IC (LDL-IC)-induced MMP-1 secretion in a dose- and time-dependent manner. Furthermore, Northern blot analysis revealed that IFN-gamma pretreatment led to a marked increase in MMP-1 mRNA. Finally, we demonstrated that PD98059 was able to block LDL-IC-induced MMP-1 secretion, regardless of whether the cells were pretreated with IFN-gamma or not, suggesting that IFN-gamma pretreatment did not alter the essential role of the ERK signaling pathway in LDL-IC-induced MMP-1 expression. In conclusion, the present study has demonstrated that IFN-gamma pretreatment augments LDL-IC-induced MMP-1 expression in U937 cells, thus elucidating an immune mechanism potentially involved in plaque destabilization.

Cardiac myxoma is rich in factor XIIIa positive dendrophages: immunohistochemical study of four cases.

Cardiac myxoma is an enigmatic tumour thought to arise from primitive cardiac mesenchymal cells. Factor XIIIa+ dendrophages are tissue histiocytes that are active in tissue repair and thrombosis. To explore whether factor XIIIa+ dendrophages play a role in cardiac myxoma morphogenesis, we stained four cases with an antiserum against coagulation factor XIIIa (FXIIIa). We also used antibodies recognizing CD34, CD31, and S-100 protein. Samples of valvular endocardium from 12 and 16 week fetuses and two adult autopsies were compared with the four myxomas. All cardiac myxomas had rounded and dendritic FXIIIa+ cells admixed with more numerous CD34+ spindle and stellate myxoma cells. The CD34+ cells formed multicellular syncytia and capillary sprouts. Many of these syncytial structures also expressed CD31 and, to a lesser extent, S-100 protein, strongly in two cases and more focally in two. Fetal subendocardium was composed of CD34+ stellate fibroblast-like cells invested with scattered FXIIIa+ histiocytes; no S-100+ cells were detected. Our findings confirm that cardiac myxomas are composed of CD34+ primitive subendocardial cells. These cells show a capacity for CD31+ endothelial differentiation. In cardiac myxoma, the CD34+ myxoma cells are accompanied by numerous FXIIIa+ dendrophages, the presence of which suggests abnormal organizing thrombus-like differentiation in cardiac myxoma morphogenesis.

Human CuZn superoxide dismutase enzymatic activity in cells is regulated by the length of the mRNA.

Single functional human CuZnSOD gene encodes two species of mRNA differing in size by 200 nucleotides in the 3'-untranslated region (UTR). We studied the expression of the CuZnSOD cDNA with different 3'- and 5'-UTR. Deletion in the 5'-end does not affect the expression of the enzyme, however, deletion in the 3'-UTR decreases the level of expression of CuZnSOD. The plasmids containing the long CuZnSOD cDNA with all polyadenylation signal sequences utilize primarily the last polyadenylation site and give a long mRNA, which produces three times more enzyme than the short mRNA lacking the last polyadenylation site and the AU-rich region.

Expression of neuron-specific enolase immunoreactivity by cutaneous and extracutaneous Langerhans-cell histiocytoses ("X").

The immunohistochemical expression of Neuron-Specific Enolase (NSE) and of S100 protein was studied in 10 cases of cutaneous and 19 cases of extracutaneous Langerhans cell histiocytoses (LCH), including acute/proliferative forms (cutaneous Letterer-Siwe disease) and chronic/granulomatous forms (eosinophilic granuloma, Hand-Schüller-Christian disease). Of the LCH cases, 18 (62%) exhibited detectable NSE-immunoreactivity as compared to 82.8% for S100. NSE expression was found more frequently and intensely within acute (as compared to chronic) forms of LCH. This result lends further support to the cellular unicity of LCH, but also suggests some degree of heterogeneity among LCH cells. It can be speculated that NSE-expression is correlated with the proliferation/activation state of (abnormal) Langerhans cells.

Congenital histiocytosis. A heterogeneous group of diseases, one presenting as so-called congenital self-healing histiocytosis.

Three cases of congenital histiocytic disorders--generalized Langerhans cell histiocytosis, generalized juvenile xanthogranuloma and so-called congenital self-healing histiocytosis are compared using histiochemical, immunohistochemical and ultrastructural methods. The results showed a typical morphological pattern of Langerhans cell histiocytosis (S 100+, CD 1+, alpha-mannosidase +) with an unusual self-healing cutaneous phenomenon. The congenital self-healing histiocytosis showed a non-Langerhans cell immunophenotype (CD 14+, CD 1-, S 100-) and morphological appearance resembling the evolutive "early" stage of juvenile xanthogranuloma. A diffuse cellular positivity of alpha-mannosidase in juvenile xanthogranuloma and congenital self-healing histiocytosis differed from a typical perinuclear globular positivity of this enzyme in Langerhans cell histiocytosis. It is concluded that congenital self-healing histiocytosis may in some cases be of non-Langerhans cell type and under this term a clinically characteristic syndrome of histiocytic proliferation of Langerhans cells or tissue histiocytes may be included.

Presence of melanophages in the normal Japanese skin.

Human skin samples were obtained from the normal peripheral portion of specimens removed from persons with various cutaneous and systemic diseases. A portion of each specimen was embedded in paraffin and another part in water-soluble embedding medium, and some was frozen in liquid nitrogen for light microscopy and histochemistry. Some specimens were also investigated by electron microscopy. In 31 of 32 specimens, cells containing brown pigment were observed in the superficial dermis. Because both acid phosphatase and Masson-Fontana staining were positive and the 3,4-dihydroxyphenylalanine reaction negative, the cells were considered to be melanophages. Electron microscopic examination revealed that these cells contained melanosome-laden phagosomes. Some fibroblastlike cells were also observed with intracellular single or multiple melanosomes. This study documents the occurrence of melanophages in the normal skin of Japanese subjects.

The major source of endogenous prostaglandin D2 production is likely antigen-presenting cells. Localization of glutathione-requiring prostaglandin D synthetase in histiocytes, dendritic, and Kupffer cells in various rat tissues.

The cellular localization of glutathione-requiring PGD synthetase, which catalyzes the predominant formation of PGD2 in various peripheral tissues, was investigated in adult rats by immunoperoxidase-staining with a polyclonal antibody specific for this enzyme. Although the 25 N-terminal amino acid residues of synthetase are 56% identical and 76% similar to those of several rat glutathione S-transferase subunits, the antibody cross-reacted only with synthetase in dot blotting and was nearly completely inactive with all transferase isozymes thus far purified. In Western blotting after SDS-PAGE of crude extracts of rat spleen, the antibody showed a single positive band at the same position as that of the purified enzyme (Mr = 26,000). The positive immunocytochemical stain was found in a number of histiocytes and/or dendritic cells in spleen, thymus, and Peyer's patch of intestine. The immunostain was also observed in such cells in lamina propria of the villus in small intestine and colon, in submucosal layer of stomach, and in Kupffer cells in liver. Immunoelectron microscopy confirmed that immunoreactivity of this enzyme was distributed in cytoplasm of those cells. Such immunoreactive cells were not observed in brain, spinal cord, kidney, heart, testis, and skeletal muscle. These observations suggest that PGD2 is produced by glutathione-requiring PGD synthetase localized in these types of APC in various tissues and may play a critical role in dictating the progression of immune responses.

Immunohistochemical characterization of the histiocytes in sinus histiocytosis with massive lymphadenopathy: analysis of an extranodal case.

We studied the morphologic, antigenic, and enzymatic characteristics of the histiocytes in an isolated extranodal case of sinus histiocytosis with massive lymphadenopathy (SHML) involving the CNS. To our knowledge, this represents the first immunohistochemically documented case of CNS SHML. The histiocytes exhibited the S-100(+), CD11c(+), alpha-1-antichymotrypsin(+) immunophenotype, which suggests that the histiocytes of SHML coexpress phenotypic characteristics of histiocytes of the mononuclear phagocytic system, and histiocytes of the interdigitating reticulum cell and Langerhan cell lineages. To examine the argument that the histiocytes in SHML may represent ordinary tissue macrophages of granulomatous inflammation, we compared the immunophenotypic characteristics of the histiocytes found in SHML to those found in xanthogranulomatous pyelonephritis (XP). We found that the histiocytes of XP have immunophenotypic characteristics of histiocytes belonging to the mononuclear phagocytic system lineage. The present study demonstrates that the histiocytes of SHML are distinct from the histiocytes of another xanthogranulomatous disorder, supporting the concept that SHML is a distinct clinicopathologic entity.

Reticulosis medular histiocítica / Histiocytic medullary reticulosis

La Reticulosis Medular Histiocítica constituye una neoplasia maligna generalmente fatal en un período corto de tiempo. Los histiocitos atípicos invaden hueso, médula ósea, higado, bazo, intestino, meninges, piel agregando nosotros laringe, localización no referida en la bibliografia consultada. Las lesiones cutáneas constituyen el 10-13% del compromiso general; consisten en tumores queratósicos ulcerados, distribuidos en tronco y miembros. Los métodos inmunohistoquimicos (lisozima, alfa, antitripsina, S-100) son actualmente otro elemento importante de diagnóstico, siendo como en nuestro caso positivos tanto en laringe como piel. La evolución es mala, falleciendo en poco tiempo por sobreinfecciones o bien hemorragias. Nuestra paciente respondió satisfactoriamente a la quimioterapia instituida, en un período de dos años de control.

Reticulosis medular histiocítica / Histiocytic medullary reticulosis

La Reticulosis Medular Histiocítica constituye una neoplasia maligna generalmente fatal en un período corto de tiempo. Los histiocitos atípicos invaden hueso, médula ósea, higado, bazo, intestino, meninges, piel agregando nosotros laringe, localización no referida en la bibliografia consultada. Las lesiones cutáneas constituyen el 10-13% del compromiso general; consisten en tumores queratósicos ulcerados, distribuidos en tronco y miembros. Los métodos inmunohistoquimicos (lisozima, alfa, antitripsina, S-100) son actualmente otro elemento importante de diagnóstico, siendo como en nuestro caso positivos tanto en laringe como piel. La evolución es mala, falleciendo en poco tiempo por sobreinfecciones o bien hemorragias. Nuestra paciente respondió satisfactoriamente a la quimioterapia instituida, en un período de dos años de control. (AU)