Introduction. Invasive tumours in Nelson's syndrome need aggressive therapy. 
Recent reports have documented the efficacy of temozolomide (TMZ) in the 
treatment of adenomas resistant to conventional management. Objective. The 
review of the literature concerning TMZ treatment of atypical corticotroph 
adenomas and a case study of 56-year-old woman who developed Nelson's syndrome. 
Treatment Proceeding. The patient with Cushing's disease underwent 
transsphenoidal adenomectomy followed by a 27-month-long period of remission. 
Due to a regrowth of the tumor, she underwent two reoperations followed by 
stereotactic radiotherapy. Because of treatment failures, bilateral 
adrenalectomy was performed. Then she developed Nelson's syndrome. A fourth 
transsphenoidal adenomectomy was performed, but there was a rapid recurrence. 
Five months later, she underwent a right frontotemporal craniotomy. Due to a 
rapid regrowth of the tumour, the patient did not receive gamma-knife therapy 
and was treated with cabergoline and somatostatin analogue for some time. Only 
TMZ therapy resulted in marked clinical, biochemical, and radiological 
improvement. To date, this is the first case of invasive corticotroph adenoma in 
Nelson's syndrome treated with temozolomide in Poland. Conclusion. In our 
opinion, temozolomide can be an effective treatment option of invasive adenomas 
in Nelson's syndrome.