The most common type of underarm lump is a parametrial breast and an enlarged lymph node. Parametrium is a congenital abnormality and is characterized by a localized raised mass. Ultrasound may indicate a uniform echogenicity of the lesion. The parametrium may also appear to be enlarged, while presenting with regular pain. Enlarged lymph nodes in the armpit may be painful to palpation, mostly secondary to inflammation of the breast, and may appear as a single enlarged lymph node. Patients with malignant tumors of the breast are also prone to metastasis to the axillary lymph nodes and may even develop fusion, which may manifest as localized pain, masses, and firmness on palpation. Lymph nodes that involve axillary veins, blood vessels, and nerves may also present with numbness and pain in the upper extremities. Lymph node enlargement caused by inflammation can be gradually reduced with timely anti-inflammatory treatment, while parametrial disease requires surgical removal if necessary.