What condition presents as a rapidly enlarging mass in adults with surrounding nontender lymphadenopathy?

The condition that presents as a rapidly enlarging mass in adults with surrounding nontender lymphadenopathy is diffuse large B-cell lymphoma. This type of lymphoma is known for its aggressive behavior and can manifest as a rapidly growing tumor, which is often accompanied by lymphadenopathy. The lymph nodes may be swollen and nontender, which is a characteristic that helps differentiate it from other conditions, such as infections or other types of cancers that may present with painful lymphadenopathy.

Diffuse large B-cell lymphoma arises from B lymphocytes and can occur in various anatomical locations, leading to varying clinical presentations, including mediastinal masses or peripheral lymph node enlargement. It tends to have a more aggressive clinical course compared to other lymphoma types, which is why prompt diagnosis and treatment are critical.

Other lymphomas or conditions may present differently or with different symptoms. For instance, follicular lymphoma typically grows more slowly and is often associated with more indolent disease progression, while Hodgkin's lymphoma may present with B symptoms such as fever and night sweats in addition to lymphadenopathy. Similarly, small cell lung carcinoma usually presents as a lung mass and may involve lymph nodes but doesn't typically present with the rapid growth and local lymphadenopathy seen in diffuse large B-cell