Differential Diagnosis for Iliac and Inguinal Lymphadenopathy

Single Most Likely Diagnosis

• Infectious lymphadenitis: This is often the most common cause of lymphadenopathy in the iliac and inguinal regions, typically resulting from bacterial, viral, or fungal infections. The proximity of these lymph nodes to the lower extremities and genital areas makes them prone to infection from these regions.

Other Likely Diagnoses

• Metastatic cancer: Cancers from the lower abdomen, pelvis, and lower limbs can metastasize to the iliac and inguinal lymph nodes. Common sources include melanoma, carcinoma of the cervix, uterus, prostate, and testes.
• Lymphoma: Both Hodgkin's and non-Hodgkin's lymphoma can present with lymphadenopathy in these regions, although it's less common than other areas like the neck or mediastinum.
• Autoimmune disorders: Conditions like rheumatoid arthritis, lupus, or sarcoidosis can cause lymphadenopathy, including in the iliac and inguinal regions, though this is less typical.

Do Not Miss Diagnoses

• Testicular cancer: Although relatively rare, testicular cancer can metastasize to the iliac and inguinal lymph nodes. Early detection is crucial for treatment outcomes.
• Pelvic or abdominal malignancies: Cancers of the ovaries, bladder, or colon can also spread to these lymph nodes. Missing these diagnoses could lead to delayed treatment and poor prognosis.
• Tuberculosis or other granulomatous infections: These can cause lymphadenopathy and have a significant impact on health if not treated properly.

Rare Diagnoses

• Castleman disease: A rare disorder that involves an overgrowth of cells in the lymph nodes, which can cause lymphadenopathy.
• Kikuchi-Fujimoto disease: A rare, self-limiting condition that causes lymphadenopathy, typically in the neck but can occur in other areas.
• Whipple's disease: A systemic bacterial infection that can cause lymphadenopathy among other symptoms, though it's exceedingly rare.
• Lymphangioleiomyomatosis (LAM): A rare lung disease that can cause lymphadenopathy, particularly in women of childbearing age.

Each of these diagnoses has distinct implications for patient management and outcomes, emphasizing the importance of a thorough diagnostic workup for iliac and inguinal lymphadenopathy.