Differential Diagnosis for Unilateral Non-Fixed Non-Tender Enlarged Groin Lymph Node in a 55-Year-Old Woman

Single Most Likely Diagnosis

• Benign lymphadenopathy: This is often due to a reactive process, which can be caused by a variety of factors including infections, inflammation, or autoimmune diseases. The fact that the lymph node is non-tender and not fixed suggests a benign cause.

Other Likely Diagnoses

• Inguinal hernia: Although the primary complaint is about a lymph node, an inguinal hernia can sometimes present with a palpable mass in the groin area that might be mistaken for an enlarged lymph node.
• Lipoma or other soft tissue tumors: These are benign growths that can occur in the groin area and might be mistaken for an enlarged lymph node.
• Infections (e.g., cellulitis, abscess): While the node is described as non-tender, some infections might present with minimal pain, especially in early stages or in immunocompromised individuals.
• Dermatological conditions (e.g., hidradenitis suppurativa): Certain skin conditions can cause lymphadenopathy due to chronic inflammation.

Do Not Miss Diagnoses

• Lymphoma: Although less common, lymphoma is a critical diagnosis to consider because it can present with painless lymphadenopathy. Early detection is crucial for treatment outcomes.
• Metastatic cancer: Cancers such as melanoma, breast cancer, or gynecologic malignancies can metastasize to groin lymph nodes. Given the patient's age, this is a possibility that cannot be overlooked.
• Tuberculosis or other granulomatous diseases: These can cause lymphadenopathy and, although less common in some regions, are important to consider due to their potential impact on health if left untreated.

Rare Diagnoses

• Kaposi's sarcoma: This is a rare cancer that can cause lymphadenopathy, especially in immunocompromised patients.
• Castleman disease: A rare disorder that involves an overgrowth of cells in the lymphatic system, which can cause lymphadenopathy.
• Rosai-Dorfman disease: A rare and benign histiocytic disorder that can cause lymphadenopathy.

Each of these diagnoses should be considered in the context of the patient's full medical history, physical examination, and appropriate diagnostic tests to determine the underlying cause of the enlarged lymph node.