A hard lump felt inside the flesh of the thigh is usually a sign of a sebaceous cyst, multiple lipocystic tumors, deep abscesses, or enlarged lymph nodes. 1. Sebaceous cysts are benign subcutaneous growths, which may be primary, or may originate from traumatic implantation of follicular epithelium into the dermis, or from acne. 2. The cause of multiple lipocystic tumors is not completely clear, mainly related to heredity, fat people have more obvious symptoms, preferably in the waist, abdomen and thighs. 3. Deep abscess is caused by infection of deep skin and muscle tissues, and is related to trauma and surgical operation. 4. Enlarged lymph nodes are mostly found in the groin, mainly caused by infections in the nearby skin and other tissues. It occurs during episodes of localized dengue, herpes zoster, syphilis, hard chancre and other infectious diseases. Feeling a hard lump inside the flesh of the thigh is recommended to consult a doctor in time and follow the doctor’s instructions for treatment.