Differential Diagnosis for a 2cm Tender Right Inguinal Lymph Node
The differential diagnosis for a 2cm tender right inguinal lymph node can be categorized into the following groups:
- Single Most Likely Diagnosis
- Inguinal lymphadenitis due to a skin infection: This is the most likely diagnosis, given the tenderness of the lymph node, which suggests an infectious or inflammatory process. The inguinal lymph nodes drain the lower limbs, genitalia, and perineal area, making a skin infection in these areas a common cause.
- Other Likely Diagnoses
- Sexually Transmitted Infection (STI): Given the location of the lymph node, STIs such as chlamydia, gonorrhea, or syphilis could be a cause, especially if there's a history of unprotected sexual activity.
- Folliculitis or Furunculosis: These are infections of the hair follicles that can cause lymphadenopathy if they become severe or if the infection spreads.
- Cellulitis: An infection of the skin and subcutaneous tissues, which can cause tender lymphadenopathy.
- Do Not Miss Diagnoses
- Malignancy (Lymphoma or Metastatic Cancer): Although less likely, malignancy can cause lymphadenopathy. It's crucial not to miss this diagnosis, as it requires prompt and specific treatment.
- Tuberculosis: TB can cause lymphadenitis, and although it's less common in some regions, it's a critical diagnosis not to miss due to its public health implications and the need for specific treatment.
- HIV: Acute HIV infection can present with lymphadenopathy, among other symptoms. Identifying HIV early is crucial for the patient's management and to prevent further transmission.
- Rare Diagnoses
- Cat-Scratch Disease: Caused by Bartonella henselae, this infection can lead to lymphadenopathy, typically after a cat scratch or bite.
- Toxoplasmosis: Although more commonly associated with cervical lymphadenopathy, toxoplasmosis can occasionally cause inguinal lymph node enlargement.
- Lymphogranuloma Venereum (LGV): A type of STI caused by certain strains of Chlamydia trachomatis, which can lead to lymphadenopathy, particularly in the inguinal region.
Workup
To work up a 2cm tender right inguinal lymph node, the following steps can be taken:
- Complete History and Physical Examination: Including questions about recent travel, sexual history, exposure to animals, and any systemic symptoms.
- Laboratory Tests:
- Complete Blood Count (CBC) to look for signs of infection or inflammation.
- Blood cultures if systemic infection is suspected.
- STI screening (e.g., chlamydia, gonorrhea, syphilis, HIV).
- TB testing (e.g., Mantoux test or IGRA).
- Imaging:
- Ultrasound of the lymph node to assess its characteristics and guide potential biopsy.
- CT scan or MRI if malignancy is suspected or if the ultrasound findings are inconclusive.
- Biopsy: Fine-needle aspiration or excisional biopsy of the lymph node may be necessary to diagnose malignancy or specific infections.
- Specific Tests: Based on the history and initial findings, additional tests might be ordered, such as toxoplasma serology or tests for cat-scratch disease.