Fig. 10.28C ). Roughly one fourth of the lesions develop after trauma, reaching a size of 1 to 2 cm within a few weeks. Curettage and cautery usually are curative. Pregnancy tumor (granuloma gravidarum) is a pyogenic granuloma that occurs infrequently in the gingiva of pregnant women. These lesions may spontaneously regress (especially after pregnancy) or undergo fibrosis, but occasionally require surgical excision.
• Cavernous hemangiomas are composed of large, dilated vascular channels. Compared with capillary hemangiomas, cavernous hemangiomas are more infiltrative, frequently involve deep structures, and do not spontaneously regress. On histologic examination, the mass is sharply defined but unencapsulated and is composed of large blood-filled vascular spaces separated by connective tissue stroma (
Fig. 10.28D ). Intravascular thrombosis and dystrophic calcification are common. These lesions may be locally destructive, and surgical excision is required in some cases. More often the tumors are of little clinical significance, but they can be cosmetically troublesome and are vulnerable to traumatic ulceration and bleeding. Brain hemangiomas are problematic, because they may cause symptoms related to compression of adjacent tissue or may rupture. Cavernous hemangiomas constitute one component of von Hippel-Lindau disease (Chapter 23), in which vascular lesions are commonly found in the cerebellum, brain stem, retina, pancreas, and liver. In some cases cerebral cavernous hemangiomas are familial, caused by mutations in one of three tumor suppressor genes called CCM1, CCM2, or CCM3
Lymphangiomas are the benign lymphatic counterpart of hemangiomas.
Simple (capillary) lymphangiomas are slightly elevated or sometimes pedunculated lesions up to 1 to 2 cm in diameter that occur predominantly in the head, neck, and axillary subcutaneous tissues. Histologically, lymphangiomas are composed of networks of endothelium-lined spaces that are distinguished from capillary channels only by the absence of blood cells.
Cavernous lymphangiomas (cystic hygromas) typically are found in the neck or axilla of children, and more rarely in the retroperitoneum. Cavernous lymphangiomas can be large (up to 15 cm), filling the axilla or producing gross deformities of the neck. These lesions are composed of massively dilated lymphatic spaces lined by ECs and separated by intervening connective tissue stroma containing lymphoid aggregates. The tumor margins are indistinct and unencapsulated, making definitive resection difficult. Of note, cavernous lymphangiomas of the neck are common in Turner syndrome.
http://ebooksmedicine.net
Glomus tumors are benign, exquisitely painful tumors arising from specialized SMCs of glomus bodies, arteriovenous structures involved in thermoregulation. Distinction from cavernous hemangiomas is based on clinical features and immunohistochemical staining for smooth muscle markers. They most commonly are found in the distal portion of the digits, especially under the fingernails. Excision is curative.
Bacillary angiomatosis is a vascular proliferation in immunocompromised hosts (e.g., patients with AIDS) caused by opportunistic gram-negative bacilli of the Bartonella family. The lesions can involve the skin, bone, brain, and other organs. Two species have been implicated:
Bartonella henselae, whose principal reservoir is the domestic cat; this organism causes cat-scratch disease (a necrotizing granulomatous inflammation of lymph nodes) in immunocompetent hosts.
Bartonella quintana, which is transmitted by human body lice; this microbe was the cause of “trench fever” in World War I.