What condition is characterized by a complex soft-tissue lesion in the anterior mediastinum in the presence of elevated serum angiotensin-converting enzyme?

The condition characterized by a complex soft-tissue lesion in the anterior mediastinum along with elevated serum angiotensin-converting enzyme levels is sarcoidosis.

Sarcoidosis is a systemic granulomatous disease that can affect multiple organs, including the mediastinum. The presence of elevated angiotensin-converting enzyme (ACE) levels is a classic laboratory finding associated with sarcoidosis. This enzyme is produced by granulomatous tissue, which is prevalent in sarcoidosis.

In the anterior mediastinum, sarcoidosis may present as enlarged lymph nodes or soft tissue lesions, which can sometimes be misinterpreted as other conditions. Thymoma and teratoma, while also possible lesions in the anterior mediastinum, do not typically feature elevated serum ACE levels. Hodgkin disease can cause mediastinal masses as well but is more commonly associated with lymphoid tissue rather than with the specific serum ACE elevation found in sarcoidosis.

Therefore, the defining characteristics of sarcoidosis in this context make it the correct choice for the presented condition.