A 70 year-old Japanese man noticed a dark-red skin plaque (3 cm in diameter) on his right hip about 25 years ago. The plaque grew gradually upto a fist-sized irregularshaped elevated skin lesion and in recent 5 years the lesion repeated growth and retardation. The lesion was examined 3 times and diagnosed as malignant lymphoma at 67 year of age, 69 year of age and 70 year of age, revealing the same histology. Histologically large anaplastic cells showed Pagetoid intraepidermal growth associating polyclonal T and B cell infiltration in dermis. The large anaplastic cells were CD2+ CD3- CD4- CD5+ CD7+ CD8+ CD25+ CD30+ CD56- T-cells. CD8 Ki-1-posotive large anaplastic cell lymphoma (LAC) was diagnosed. PCR analysis of the DNA extracted from the large anaplastic cells in paraffin section showed oligoclonal bands of T-cell receptor gene B chain, suggesting a neoplastic nature of the cells. But the skin lesion showed involution into small one without any therapy. Dermatologically this lesion was diagnosed as solitary type Pagetoid reticulosis (Woringer-Kolopp disease), because of a long clinical course. Considering the clinical course and the examination results, secondary epidermotrpic large anaplastic cell lymphoma in solitary type Pagetoid reticulosis was suggested. Pagetoid reticulosis might be one of the precurssor lesions of cutaneous Ki-1-positive large anaplastic cell lymphoma.