Transformation Of Lymph Node Sinuses Research Articles

An Angiomyomatous Hamartoma With Features of Vascular Transformation of Sinuses in the Mediastinal Lymph Node of a Beagle Dog.

Two similar benign, nonneoplastic vascular lesions have been described in the lymph nodes of humans and animals: angiomyomatous hamartoma (AMH), which is characterized by the replacement of lymphoid tissue by blood vessels, smooth muscle, and fibrous tissue, and vascular transformation of sinuses (VTS), which is considered a reactive transformation of lymph node sinuses into capillary-like vascular channels. We hereby report a lesion with features common to both lesions in the mediastinal lymph nodes of a 1-year-old beagle dog in a 1-month toxicity study. Grossly, enlargement and red discoloration were observed, while microscopically, the lesion was characterized by effacement of the lymph node parenchyma with replacement by mature blood vessels, smooth muscle, and fibrous tissue, associated with lymphoid atrophy, which is consistent with AMH. However, multifocal areas of anastomosing or plexiform capillary-like channels lined by normal to slightly plump endothelium, similar to those described for VTS, were also present. Immunohistochemistry analysis revealed abundant positive staining for smooth muscle actin and endothelial cells (von Willebrand factor/factor VIII) and the absence of proliferation (Ki67). In conclusion, these lesions most likely represent a mixture of both AMH and VTS.

Immunohistochemical Analysis of Endothelial Cells in Vascular Transformation of Lymph Node Sinuses: Vascular or Lymphatic Differentiation?

Vascular transformation of sinuses (VTS) is an uncommon and benign lesion, defined by conversion of lymph node sinuses into complex, anatomizing and endothelial-lined channels. Despite the name of VTS, which implies a change in differentiation from lymphatic to vascular endothelium, very few studies have systematically examined VTS with modern immunohistochemical markers commonly used in clinical laboratories. It is unclear whether endothelial cells in VTS display pure vascular or lymphatic differentiation, or both. A total of 11 cases with a diagnosis of VTS (identified in the tissue archives of the Cleveland Clinic between 1992 and 2015) were reviewed and confirmed. Twenty cases of benign lymph nodes without specific diagnoses were used as control tissues. Immunohistochemical stains were performed on formalin-fixed, paraffin-embedded lymph node tissue using an automated immunohistochemistry platform with antibodies against CD31, CD34, D2-40, and ERG. Positivity in the VTS lesions was defined as distinct expression in the appropriate cell compartment in ≥20% of cells. In control cases, staining was evaluated in both vascular and lymphatic channels-vascular structures were identified by presence of red cells or well-formed vascular walls and lymphatics by anatomic location and absence of vascular features. In the VTS lesions, D2-40 expression was absent in the lesional endothelial cells of 5/11 (45%) cases. In the cases lacking D240 expression, uninvolved lymphatic endothelium maintained expression. CD34 expression was also seen in 6/11 (54%), CD31 was seen in 10/11 (90%), and ERG expression was seen in all cases. In all the control cases, D240 expression was exclusively seen in lymphatic endothelial cells and not seen in vascular endothelial cells (eg, vascular channels in the hilum). CD34 was weakly positive in the lymphatic endothelium of only 7/20 (35%) control cases, but expressed in 20/20 (100%) control cases in the vascular endothelium. 20/20 (100%) of control cases showed expression of CD31 and ERG in both vascular and lymphatic endothelium. VTS lesional endothelial cells demonstrate patterns of vascular markers that show mixed blood vascular and lymphatic features. There appears to be a degree of alignment toward endothelial differentiation with decreased expression of D2-40 in some cases.

Intussusceptive lymphangiogenesis in vascular transformation of lymph node sinuses

Numerous lymphatic anastomosing channels in the lymph nodes are the most demonstrative finding of the rare lesion termed “vascular transformation of lymph node sinuses” (VTS). The mechanism of lymphatic vessel formation in VTS has not been studied. Vessel intussusception contributes to vascular expansion, and intraluminal pillars/posts, interstitial tissue structures or larger pillars (ITSs) and folds are the hallmarks of this process in blood vessels. The aim of this work is to assess whether these hallmarks of intussusception occur in VTS lymphatic vessels, indicating intussusceptive lymphangiogenesis. For this purpose, specimens of five cases of VTS were used for serial histological sections, immunohistochemistry and immunofluorescence in confocal microscopy, which enabled us to demonstrate the 3D image that defines the pillars. The studies showed a) meshworks of lymphatic vessels, which form complex loops, resembling sinuses of lymph nodes, b) presence of intralymphatic pillars, ITSs and folds, with a cover of lymphatic endothelial cells expressing podoplanin and a varying-sized connective core (e.g. collagen), and c) increase of vessel meshwork and linear arrangement, splitting and fusion of ITSs, pillars and folds, with remodelling and segmentation. In conclusion, the development of lymphatic vessel loops, ITSs, pillars and folds with segmentation in VTS supports intussusceptive lymphangiogenesis. This mechanism of intussusception is of interest because it participates in VTS histogenesis, contributes to general knowledge of intussusceptive lymphangiogenesis, which has received less attention than intussusception in blood vessels, and provides a basis for further studies in other lymphatic conditions.

Mesothelial Cells Within Vascular Transformation of Mediastinal Lymph Node Sinuses

Vascular transformation of lymph node sinuses represents a rare benign entity mimicking malignant counterparts such as nodal Kaposi sarcoma. The presence of mildly atypical benign mesothelial cells within nodal sinuses raises the possibility of metastatic malignancy. Herein, a rare case of vascular transformation of lymph node sinuses with reactive sinusoidal mesothelial cells is outlined as a unique benign pathology and a potential mimicker of a malignant collision tumor.

DIAGNOSTIC EXERCISE

Angiomatoid lesions in a lymph node associated with a thyroid carcinoma of a dog were restricted to the subcapsular and medullary sinuses. Lymphoid atrophy was present, but nodal architecture was not distorted and normal structures were not invaded. Immunohistochemical staining indicated that the vascular spaces formed by spindloid cells were lined by endothelium with a low mitotic index. The spindloid cells were positive for smooth muscle actin, vimentin, and desmin and thus were likely to be fibroblasts, myofibroblasts, smooth muscle cells, and/or pericytes. These features are comparable to vascular transformation of lymph node sinuses in humans (nodal angiomatosis), a nonneoplastic condition often associated with mechanical or functional blockage of efferent lymphatics and veins.

Lycat and cloche at the Switch Between Blood Vessel Growth and Differentiation?

See related article, pages 1057–1064 The formation of the cardiovascular system starts in the mouse embryo at approximately embryonic day (E)7.0 to E7.5. The first blood vessels in the extraembryonic membranes, the major intraembryonic vessels, and the heart form by vasculogenesis, the in situ differentiation of mesodermal cells that give rise to “blood-islands.” The latter are composed of hemangioblasts, the common precursors of endothelial and blood cells. Hemangioblasts situated in the lumen of the blood islands will further differentiate into hematocytoblasts, the precursors of all 3 lineages of blood cells. In contrast, hemangioblasts lining the walls of the blood islands will give rise to angioblasts that form endothelial cells.1 Migrating angioblasts from the proximal lateral mesoderm assemble symmetrically at the lateral sides of the embryo to establish 2 preendocardial tubes. They fuse to give rise to the primordial heart.2 While vasculogenesis is still proceeding, the uniform blood islands begin to remodel to a network of large and small vessels by the process of angiogenesis, preferentially intussusceptive microvascular growth.3,4 Gene expression and targeting studies have identified vascular endothelial growth factor and its 2 receptors, KDR/flk-1 and flt-1, as critical for the formation and early remodeling of the blood islands. Vascular endothelial growth factor is produced by endodermal and mesodermal cells at the onset of hemangioblast formation, whereas its receptors are expressed in the future endothelial cells lining the blood islands.5 Flk-1−/− embryos lack blood islands throughout the embryo and yolk sac.6 In flt-1−/− embryos, blood islands do not properly remodel but form large blood channels.7 Inactivation of a single vascular endothelial growth factor allele caused multiple embryonic malformations including the heart, rudimentary dorsal aortae, and a reduced number of blood cells.8,9 All deletions were lethal between days E8.5 and E11 to …

Hemosiderotic fibrohistiocytic lipomatous lesion: clinical correlation with venous stasis

Hemosiderotic fibrohistiocytic lipomatous lesion (HFLL) is a recently proposed lipomatous entity. HFLL was originally suggested to be a benign reactive lesion arising due to an antecedent trauma. We report two patients with HFLL who also suffered from chronic vein insufficiency due to varicose involving deep veins of the low limbs. Both patients were middle-aged women with solitary, poorly circumscribed subcutaneous lesions on the lower extremities. Histopathological examination revealed typical features of HFLL. We think that the consistent clinical features such as advanced age, female sex predilection, and specific location along with distinctive histopathological features allow the suggestion that impaired blood circulation, to wit, venous stasis is involved in the pathogenesis of HFLL. We hypothesize that the proliferation of spindled fibroblastic and myofibroblastic cells and capillaries, erythrocyte extravasation, and hemosiderin deposition with lipomatous tissue of HFLL may simply represent an exaggerated tissue response to venous stasis in which elevated venous and capillary pressures, oxygen saturation, and edema stimulate the proliferation of the above mentioned elements and lead to erythrocyte extravasation. A similar histopathological pattern is seen in acroangiodermatitis of Mali and vascular transformation of lymph node sinuses, and these conditions are also associated with impaired blood circulation.

Expression of D2‐40 in lymphatic endothelium of normal tissues and in vascular tumours

To evaluate the expression of D2-40 in normal lymphatic endothelium and vascular tumours or tumour-like lesions of the skin and soft tissue. D2-40 is a novel monoclonal antibody to a Mr 40 000 O-linked sialoglycoprotein that reacts with a fixation-resistant epitope in lymphatic endothelium. Formalin-fixed paraffin-embedded sections from 30 normal tissue samples, including skin, soft tissue, stomach, and colon, and 84 vascular tumours or vascular tumour-like lesions were immunostained with monoclonal antibodies to D2-40 and CD31. Normal lymphatic endothelial cells in all normal tissues expressed D2-40. Its positive staining delineated flattened channels or open spaces lined by a single layer of endothelial cells whose lumena were sometimes filled with lymphocytes. Ten of 10 cases of lymphangioma, nine of 10 Kaposi's sarcomas (KSs), one of five spindle cell haemangiomas, one of one reactive angioenodotheliomatosis, one of one vascular transformation of lymph node sinuses, three of three Dabska tumours, one of 10 epithelioid haemangioendotheliomas (HEs) and seven of 15 angiosarcomas were positive for D2-40. Positively staining angiosarcomas were characterized by epithelioid or papillary endothelial cells. Twenty-two non-spindle cell haemangiomas, one retiform HE and one Kaposiform HE, and five glomus tumours were negative for D2-40. In comparison, CD31 was expressed in five of 10 lymphangiomas, nine of 10 KSs, 27 of 27 haemangiomas, three of three Dabska tumours, 10 of 10 epithelioid HEs, 15 of 15 angiosarcomas and one of one each of retiform HE, Kaposiform HE, reactive angioendotheliomatosis, and vascular transformation of node sinuses. Five glomus tumours were negative for CD31. The monoclonal antibody D2-40 is a highly sensitive and specific marker of lymphatic endothelium in normal tissue and a subset of vascular lesions, including KS, Dabska tumour, and lymphangioma. The findings support the concept that these tumours show at least partial lymphatic endothelial differentiation. Subsets of angiosarcomas and HEs show both vascular and lymphatic endothelial differentiation. D2-40 can be used in a panel of markers to classify vascular tumours. There is no requirement for epitope retrieval. This novel monoclonal antibody also has the potential for increasing the accuracy of detection of lymphatic invasion in primary tumours and could be widely applied for this purpose in surgical pathology.

Vascular Transformation of Sinuses in Lymph Nodes

Vascular transformation of lymph node sinuses (VTS) is characterized by conversion of nodal sinuses into capillary-like channels, often accompanied by fibrosis. A detailed study of this entity, based on 76 cases, showed that the morphologic spectrum was much broader than that originally described. The vasoproliferative process caused variable expansion of the subcapsular, intermediate, and medullary sinuses of the lymph nodes and involved single or multiple lymph nodes in a diffuse or segmental fashion. The proliferated vessels formed anastomosing narrow clefts, rounded spaces of different sizes, plexiform channels, or solid spindled to plump cellular foci and often were associated with variable degrees of sclerosis. The vascular spaces were empty, filled with lymph-like fluid, congested with blood, or occasionally thrombosed; extravasation of red cells was common. Several patterns were commonly observed in an individual case. Less common features included perivascular fibrin deposition and the presence of eosinophilic globules. Vascular thrombosis was identified only rarely in extranodal vessels available for histologic assessment. The more cellular forms of this vascular transformation may be mistaken for Kaposi's sarcoma, but can be distinguished from it by the pure sinusoidal distribution, a lack of well-formed spindle cell fascicles, the associated fibrosis, the maturation of the spindle cells into well-formed vascular channels toward the capsular aspect, and the failure of this process to involve the capsule itself, which is frequently affected by Kaposi's sarcoma.

Plexiform vascularization of lymph nodes: An unusual but distinctive lymphadenopathy in cats

A distinctive lymphadenopathy in nine cats, four of which were of the Longhair breed, was characterized by capillary vasoproliferation and lymphoid atrophy. It occurred in the cervical or inguinal regions. The animals were, apart from local manifestations, healthy at the time and remained so subsequently. In the absence of any clinical or morphological evidence for viral, neoplastic or developmental aetiologies, we postulate an ischaemic pathogenesis for the lesions which may be related to human “vascular transformation of lymph node sinuses”. The lesions appear to be by no means a rare cause of non-neoplastic lymphadenopathy in domestic cats, since they constituted over 5 per cent of surgical biopsies of cat lymph nodes seen in the past 5 years. The lesions merit wider recognition and investigation.