Mycosis fungoides: disguising malignant nature beneath a benign manner

Early cutaneous T-cell lymphomas (T-CCL) may mimic clinical manifestations of various chronic dermatoses combined with less informative diagnostic results. This is due to a fact that at the onset of lymphoproliferative diseases, primary histological, immunological, and immunohistochemical testings are characterized by low specificity. Therefore, it's often difficult to verify a diagnosis of T- CCL, and this requires a case monitoring of a patient, repeated laboratory tests and participation of various specialists to provide a comprehensive timely conclusion on nature of a developing skin disease. The paper is focused on importance of interdisciplinary interaction and a combined approach to establish a final clinical diagnosis of T-CCL Two clinical case reports reflecting a challenging diagnosis of the disease and factors of conversion of chronic dermatosis into mycosis fungoides are presented. As for the former, a discrepancy is reported between a skin disease and histological results. According to the observation analysis, repeated clinical diagnostic measures and a comprehensive differential diagnosis with mycosis fungoides that can provide early detection of dermatosis conversion into T- CCL and the most efficient management approach, should be performed. The latter case demonstrates an issue of long-term correct diagnosis associated with dermatosis progression due to lack of therapy combined with high risks of a lymphoproliferative disease. Repeated histological examinations should be carried out because some chronic dermatoses may be precursors of mycosis fungoides while sometimes malignant transformation lasts over the decades. Consideration of unfavorable predictive signs and repeated biopsies to verify a diagnosis of T- CCL play an important role in prevention of a conversion of a chronic dermatosis into a lymphoproliferative disease. Increased medical alertness and strict adherence to diagnostic algorithms can improve quality of medical care in these patients. These principles provide an opportunity to detect complications in a timely manner, to adjust therapy and to prevent dermatosis progression. As a result, this leads to improved quality of life and life expectancy in patients. KEYWORDS: chronic dermatoses, parapsoriasis, eczema, mycosis fungoides, cutaneous T-cell lymphoma, lymphoproliferative diseases, interdisciplinary approach, conversion. FOR CITATION: Tlish M.M., Kuznetsova T.G., Hadzh D.G., Lazarev V.V., Naatyzh Zh.Yu. Mycosis fungoides: disguising malignant nature beneath a benign manner. Russian Medical Inquiry. 2025;9(6):333–338 (in Russ.). DOI: 10.32364/2587-6821-2025-9-6-6