Can an infected pilinadal cyst cause painful swollen lymph nodes in upper inner thighs?

Yes. Its well known that the groin nodes, those in the upper inner thigh, respond to various disease processes especially in the thigh, perineal area and buttock region where the pilonidal abscess can arise. These nodes are particularly susceptible to infection and malignancies in this region, which then travel via the regional lymphatics to the node bearing areas in the groin.