The LYMF Foundation - Lymphatic Terminology/Thomas Colby, M.D.

Lymphangiomatosis Terminology with Brief Explanations

Written by: Thomas V. Colby MD; Professor of Pathology, Mayo Clinic College of Medicine

What are the lymphatics?

The lymphatics are a vascular system in the body that carry lymph fluid. Lymph nodes are part of the lymphatic system. The lymphatics are found throughout the body and in most organs. The lymphatic network appears in the sixth week of embryonic development. Lymphatic vessels are lined by endothelial cells, which are similar to the lining cells of blood vessels. The lymphatics have valves that allow the fluid to flow only in one direction. When the lymphatics are dilated the valves don’t work well.Abnormalities of the lymphaticsThere are many abnormalities of the lymphatics. They may be to primary defects of the lymphatics or caused by some other process (secondary). They may be congenital (present at birth) or acquired (developing after birth). Abnormalities may be restricted to one site or widespread involving multiple sites and/or organs in the body.

Lymphangiectasia (adjective – lymphangiectatic)

This term refers to dilation of normal lymphatic vessels. Lymphangiectasia is commonly secondary to something obstructing the downstream lymphatic vessels.LymphedemaThis refers to the accumulation of fluid, usually in the extremities, due to stasis of lymph fluid, usually secondary to obstruction. The fluid leaks out of the lymph vessels and produces a thickening of the skin and underlying tissues called lymphedema.

Lymphangioma

A localized abnormality of lymphatics, usually with an increase in the number of lymph vessels. It is not clear whether lymphangiomas are true neoplasms or peculiar congenital abnormalities. Lymphangiomas vary from spots to large masses composed of dilated lymphatic vessels (cystic lymphangioma or so-called cystic hygroma). Cystic lymphangiomas feel like a well-circumscribed ball of fluid. Their size may wax and wane. Lymphangiomas may be located in the head and neck, the chest the abdomen, the extremities, and at many internal sites. Some are found as masses in childhood, whereas others are recognized later in life. Microscopically, lymphangiomas have spaces lined by lymphatic endothelial cells with intervening tissues that may show lymphocytes (white blood cells) and sometimes smooth muscle. The smooth muscle is normal appearing smooth muscle which is actin ⊕, desmin ⊕, and HMB-45 ⊖ on “special stains” under the microscope.

Lymphangiomatosis

This term refers to a lymphangioma that affects soft tissue and/or organs in a widespread or multifocal fashion and hence is not a single localized mass. The various possibilities for the sites/organs affected is almost too numerous to list. Lymphangiomatosis may involve adjacent organs/sites in one part of the body or be widespread throughout the body.

Lymphangiosarcoma

A lymphangiosarcoma is a malignant tumor (a cancer) that shows features of malignant lymphatic cells.Lymphangiomyoma This is a distinct tumor usually seen in the abdomen associated with a proliferation of lymph vessels (the “lymphangio” portion of lymphangiomyoma) and smooth muscle cells (the “myoma” portion of lymphangiomyoma). The smooth muscle cells differ from normal smooth muscle in that they have distinct features under the microscope and with “special stains;” they HMB-45 ⊕ .

Lymphangiomyomatosis

This refers to more diffuse or multifocal involvement by lymphangiomyoma, usually in the retroperitoneum/abdomen.Lymphangioleiomyomatosis (sometimes lymphangiomyomatosis is also used for this).This refers to a distinctive lung disease in which there is cystic change in the lung and proliferation of abnormal smooth muscle cells that are similar to the abnormal smooth muscle cells (HMB-45 ⊕) seen in lymphangiomyoma.

How do lymphangioma and lymphangiomatosis manifest? What symptoms to they produce?

Lymphangiomas and lymphangiomatosis are characterized by abnormal, often dilated, lymphatic vessels containing lymph fluid. As such they produce a mass or swelling that feel fluid filled; they can be localized or widespread depending on the extent of involvement and the organs or tissues affected. For example: lymphangiomatosis of the spleen produces a diffusely enlarged spleen due to diffuse involvement of that organ by dilated lymph vessels. A lymphangioma of the spleen would produce a focal swelling in the spleen. A similar analogy can be applied to other organs and sites.

How are abnormalities of the lymphatics diagnosed by your doctor?

In some cases the physical examination shows features typical enough for a diagnosis. In other cases a biopsy must be taken in which abnormal lymphatics are identified under the microscope and the appropriate terms above applied depending on the features present.

What sites are involved by lymphangiomas and lymphangiomatosis?

Lymphangiomas and lymphangiomatosis may involve a large number of sites, with the exception of the central nervous system. Virtually any other organ or soft tissue site may be involved including: skin, soft tissues of the extremities and the trunk, soft tissues of the head and neck, tongue, salivary glands, liver, spleen, esophagus, stomach, small intestine, large intestine, retroperitoneum, omentum, mesentery, mesocolon, mediastinum, lymph nodes, skeletal muscle, etc.

How are lymphangiomas and lymphangiomatosis treated?

This is very complicated and depends on the site(s) involved and the problems that the lymphangioma or lymphangiomatosis is causing. Localized tumors can be surgically removed but often the abnormal lymphatics extend further than apparent to the naked eye and some cases may recur as a result of this. When lymphangiomatosis is diffuse or widespread surgical removal is not feasible and other treatments and palliative measures need to be tried.

References

Dorland’s Illustrated Medical Dictionary, 28^th Edition, WB Saunders, Philadelphia, 1994.2.

Rhodin JAG. Histology, A Text and Atlas, Oxford University Press, New York, 1974.3.

Weiss SW and Goldblum JR.

Enzinger and Weiss’ Soft Tissue Tumors, 4^th Edition, Mosby, St. Louis, 2001.