Sexually Transmitted Infections (STIs): Given the location of inguinal lymphadenopathy, STIs such as gonorrhea, chlamydia, or syphilis are common causes, especially in sexually active males. These infections often present with lymph node enlargement in the inguinal region.

Cellulitis or Skin Infections: Infections of the skin or soft tissues in the lower limbs can cause inguinal lymphadenopathy due to the lymphatic drainage pathway.
Fungal Infections: Such as tinea cruris (jock itch) or other dermatophyte infections, which can cause lymph node enlargement in the groin area.
Viral Illnesses: Like infectious mononucleosis (mono) caused by Epstein-Barr virus, though this is more commonly associated with cervical lymphadenopathy, it can also involve inguinal nodes.

Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can present with lymphadenopathy, including in the inguinal region. Although less common, missing this diagnosis could have severe consequences.
Testicular Cancer: Metastasis to inguinal lymph nodes can occur, especially with testicular cancers like choriocarcinoma or other germ cell tumors.
Melanoma: Malignant melanoma of the lower limb can metastasize to the inguinal lymph nodes, making it a critical diagnosis not to miss.

Filariasis: In endemic areas, filarial infections (like Wuchereria bancrofti) can cause lymphadenopathy, including in the inguinal region, due to the parasitic infection.
Tuberculosis: Though more commonly associated with pulmonary symptoms, extrapulmonary tuberculosis, including lymph node tuberculosis, can occur in the inguinal region, especially in immunocompromised individuals or those from endemic areas.
Kaposi's Sarcoma: This rare cancer can cause lymphadenopathy and is more common in immunocompromised patients, such as those with HIV/AIDS.