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Localized lymphedema may play role in pathogenesis of giant angiofibromas in tuberous sclerosis complex

Localized lymphedema may contribute to the formation of large disfiguring angiofibromas in patients with tuberous sclerosis complex, according to new data.

Researchers studied 42 lesional specimens and peripheral blood from one of two potential study patients, performing clinicopathologic, immunohistochemical and molecular biologic studies. TSC1 and TSC2 alterations were analyzed, and screening for small mutations was performed.

Histopathologic examination revealed a number of unusual features, including:

• Multinucleated giant cells containing multiple intracytoplasmic vacuoles
• Touton-like cells
• Emperipolesis
• Pagetoid dyskeratosis
• Vacuolar alteration at the dermoepidermal junction
• Civatte bodies
• Melanophages in the subjacent dermis

Researchers also detected numerous dilated lymphatic vessels that indicated localized lymphostasis “probably caused by secondary lymphedema.” Immunohistochemical study confirmed the lymphatic nature of the vessels.

A substitution on position c.2251C>T — resulting in a nonsense mutation R751X in fragment 20.2 — was revealed by genetic testing for TSC1 and TSC2 gene mutations.

“The numerous dilated lymphatic vessels we detected microscopically … can be regarded as a sign of lymphostasis, probably caused by secondary lymphedema,” the researchers wrote. “Thus, giant angiofibromas appear to attain their great size as a result of expansion of the mesenchymal tissues.”