The thirty-five-year-old woman had been experiencing dyspnea on exertion since her second child's birth five years before presenting to hospital A, where she was diagnosed with lymphangioleiomyomatosis (LAM) based on video-assisted thoracoscopic surgery lung biopsy and referred to our hospital. She was treated with sirolimus for one year. Although her subjective symptom of dyspnea improved, she found that her amenorrhea had persisted for six years. A blood test revealed high prolactin (PRL) levels of 98 ng/mL and head magnetic resonance imaging revealed a pituitary adenoma, which was complicated by a prolactinoma. We continued with follow-up observation without any pharmacotherapy for the prolactinoma. However, she was administered oral cabergoline (0.25 mg per week) when her PRL levels were elevated to 250 ng/mL 38 months after therapeutic intervention with sirolimus. For the next 14 months, her respiratory function and PRL concentration both demonstrated improvement and her condition did not worsen any further. It has been reported that prolactin may exacerbate LAM. Our case suggests that a clinical reduction in PRL levels may also improve LAM.