Immunohistochemical study of stromal and vascular components of tonsillar polyps: high endothelial venules as participants of the polyp’s lymphoid tissue

Abstract

Tonsillar polyps are nonneoplastic lesions usually composed of variable amounts of lymphoid and vascular and connective tissues. All of them are generally assumed to be hamartomatous proliferations, but the profile of vascular and connective components has yet to be explored. The vascular system of the tonsils is complex and includes highly specialized structures (i.e., high endothelial venules (HEVs)) involved in lymphocyte homing into lymphoid tissues. In 14 tonsillar polyps and 26 control tonsils, an immunohistochemical study was performed using CD34 (blood vessels and HEVs), MECA-79 (HEVs), D2-40 (lymphatic vessels), Ki-67, collagens I and III, fibronectin, and tenascin-C. The polyps showed increased total lymphatic area, whereas the number of blood vessels and lymphatics and the blood vascular area did not differ significantly from those of control tonsils. Rare Ki-67+ endothelial cells were found. In the polyps, we detected, possibly for the first time, HEVs amid lymphoid tissue, and that the amount of the latter correlated positively with HEV density. The polyps also presented lesser amounts of fibronectin and collagens I and III than in normal tonsils, which were distributed in a disorganized fashion. Tenascin-C expression was uncommon in the polyps and control tonsils. Tonsillar polyps are composed of disorganized connective tissue and lymphatic channels which can be considered hamartomatous proliferations. However, the lymphoid component is possibly reactive due to its relationship with the HEVs. The highly differentiated phenotype of the HEVs and their complex biology are not in agreement with what would be expected for a component of hamartomatous nature.

Lymphangioma of the Palatine Tonsil

“…This antibody recognizes a carbohydrate epitope expressed in high endothelial venules, specialized structures involved in lymphocyte homing into lymphoid tissues. 11 Lastly, immunohistochemical staining for fibronectin and collagens I and III revealed a decreased and disorganized distribution of these extracellular matrix proteins in lymphangiomas compared with normal tonsils. 11…”

“…16 Furthermore, a study of 14 cases of tonsillar lymphangioma found no gross evidence of lymphatic obstruction in the lesions or associated resected normal tonsils, even after serial sectioning of the tissue specimens. 11 This suggests that another mechanism is likely responsible for the pathogenesis of these tumors.…”

A Rare Cause of Dysphagia in Children

“…Moreover, the tonsil is a less common site for the development of lymphangiomatous lesions. 2,3 The head and neck region is the most common site of lymphangiomatous lesions. Most arise in the skin and subcutaneous tissues, but other sites include the larynx, parotid gland, mouth, and tongue.…”

“…2 Of the 214 cases of orbital cavernous hemangioma referred to our center, none displayed any obvious inflammatory cells. 3 Recently, however, a case of orbital cavernous hemangioma that showed obvious inflammatory cell infiltration in the interstitium was presented at our center. The unique nature of this case, which is quite different from that of other typical orbital cavernous hemangiomas, prompted us to compile this case report.…”

“…1 Benign tumors of the tonsils are rarely seen, compared with malignancies. 2,3 The polypoid masses tend to have varying degrees of fibrous, adipose, and lymphoid components, and they tend to ocur most commonly in the lower gastrointestinal tracts. 4 Lymphangiomatous polypoid lesions also arise from the lymphatic and vascular systems but are histologically different than a typical lymphatic malformation.…”