Abstract
Mycosis fungoides (MF) is the most common form of cutaneous T-cell lymphoma, a type of skin cancer that involves malignant T lymphocytes infiltrating the skin. It typically presents as flat, red, scaly patches (erythematous plaques). A rare variant known as folliculotropic mycosis fungoides (FMF) differs in both its clinical behavior and histologic features. FMF is characterized by infiltration of hair follicles by malignant T cells and may present as deep, painful nodules that resemble common skin conditions such as nodulocystic acne, a severe form of acne with cysts and inflamed nodules. This clinical mimicry can lead to misdiagnosis, delayed treatment, and potentially worse outcomes. Given its deceptive presentation and potential for progression, FMF should be considered in cases of persistent, treatment-resistant acneiform lesions, particularly in older patients. Here, we describe the case of an 85-year-old man with facial and truncal nodules initially treated as acne, who was ultimately diagnosed with FMF after histopathologic evaluation. This case underscores the importance of early biopsy and clinical suspicion to avoid misdiagnosis and ensure appropriate management.