Primary benign vascular tumors of lymph nodes.

Vascular neoplasms of lymph nodes are uncommon yet morphologically diverse, including multiple entities with a varied and sometimes confusing nomenclature (1).

Benign vascular tumors arising primarily in lymph nodes are rare and, except for a multi-institutional study including 39 cases (2), the few articles in the literature are single case reports (3,4,5,6,7,8,9). The various types of vascular tumor seen in soft tissues and other organs, particularly hemangioma and hemangioendothelioma, are reproduced in the lymph nodes (10). The spectrum of vascular proliferations in lymph nodes ranges from the benign vascular hyperplasias that accompany various infections and the peculiar form of vascular transformation of sinuses (see Chapter 48) to the malignant neoplasms of Kaposi sarcoma (see Chapter 85) and angiosarcoma. In the largest study of benign vascular tumors of lymph nodes, Chan and colleagues (2) proposed a classification of five histologic types: (a) hemangioma and its variant, (b) angiomyomatous hamartoma, (c) hemangioendothelioma and its variant, (d) polymorphous hemangioendothelioma, and (e) lymphangioma. Benign vascular tumors of lymph nodes are less common than either non-neoplastic vascular hyperplasia or Kaposi sarcoma. They are, in most cases, incidental findings with no clinical significance. However, it is important to recognize them to avoid a misdiagnosis of Kaposi sarcoma or angiosarcoma.

Benign vascular tumors of lymph nodes may be found incidentally in the course of various surgical explorations or present clinically as enlarged lymph nodes. The average diameter reported is 2 to 3 cm, and the location is variable, mostly in peripheral lymph nodes, which are more accessible to observation and removal. Angiomyomatous hamartoma has been seen only in inguinal lymph nodes (2). Patients with hemangioma are more often young to middle-aged and predominantly male (2). Hemangiomas with a hamartomatous appearance are more likely to be seen in children (3,8).

Hemangioma in lymph nodes is identical to its counterpart in the soft tissues, forming a discrete or diffuse mass (1).

Hemangioma may be capillary, cavernous, or mixed (Figs. 84.1 and 84.2). Capillary hemangiomas appear as a conglomerate of capillary vessels lined by a single layer of flat endothelial cells. They resemble a pyogenic granuloma or simply granulation tissue (1,2). Cavernous hemangiomas include large, irregular spaces packed with erythrocytes and occasional thrombi with partial organization (2,5). Hemangiomas may be well circumscribed and include a scanty edematous or fibrosed stroma. More often, they are centered on the lymph node hilum or medulla (1). The vascular channels may be empty or engorged with blood. Outside the vascular growth, the lymph node parenchyma is well preserved and sometimes exhibits mild activation of the germinal centers (8). Epithelioid hemangiomas differ only by their vascular lining, which is composed of plump rather than flat endothelial cells (2).