Follicular mucinosis is frequently associated with follicular mycosis fungoides, but its association with adult T-cell leukemia-lymphoma (ATLL) is extremely rare. We report a case of a 50-year-old female patient with a history of ATLL, after multiple treatments, with residual/recurrent skin tumors in the forehead and legs. Biopsy of a skin tumor from the forehead revealed a perifollicular and intrafollicular atypical lymphoid infiltrate with abundant mucin deposition. Immunohistochemical stains showed that the atypical cells were positive for CD3, CD4, and CD25. Reverse transcription polymerase chain reaction performed on the tissue sections confirmed the presence of human T-cell leukemia virus in the biopsies of skin tumors. To our knowledge, this is only the third reported case of a follicular mucinosis in the setting of ATLL.