Paclitaxel-Induced Periarticular Thenar Erythema with Onycholysis Syndrome.

Introduction: Periarticular thenar erythema with onycholysis (PATEO) syndrome is a rare subtype of hand-foot syndrome seen in patients undergoing taxane-based chemotherapy. It presents as erythematous to violaceous plaques on the dorsum of hands, feet, and around the Achilles tendon along with nail changes, particularly onycholysis. Case Presentation: A 39-year-old female on paclitaxel chemotherapy for stage IIIA (T3N2aM0) invasive ductal breast carcinoma, presented with mildly tender erythematous to violaceous plaques involving the dorsa of bilateral hands and feet, in the periarticular areas of the Achilles tendon, with facial involvement. All fingernails showed shortening, orange-red chromonychia, Beau's lines, onychoschizia, and subungual debris. The toenail involvement was relatively less severe, with distal onycholysis being the predominant finding. The patient showed significant improvement in cutaneous lesions with topical steroid therapy and was advised cold water immersion during subsequent chemotherapy infusions. Discussion: A shorter interval between cycles and a higher cumulative number of cycles correlate with severity of dermatitis and nail involvement. Rarely, periocular and facial involvement can occur concurrently with PATEO syndrome. This case is being reported to increase awareness about this entity facilitating early diagnosis and treatment.

Dasatinib-Induced Transverse Melanonychia.

Introduction: Transverse melanonychia, characterized by grey to black pigmented bands traversing the nail plate, can occur as a side-effect of certain medications. While no documented reports specifically associate dasatinib, a tyrosine kinase inhibitor used in the treatment of chronic myeloid leukaemia (CML) and acute lymphoblastic leukaemia, with nail changes, we present a case of transverse melanonychia possibly related to dasatinib therapy. Case Report: A 54-year-old male with CML, receiving dasatinib for 1.5 years, presented with transverse pigmented lines involving all fingernails and toenails. Clinical examination revealed discrete bands of transverse melanonychia in the nails. Onychoscopy of all finger- and toenails revealed multiple longitudinal grey lines within transverse grey bands of homogeneous chromonychia. Based on clinical presentation, onychoscopic features, and temporal association with dasatinib therapy, a provisional diagnosis of dasatinib-induced transverse melanonychia was made. Discussion: The exact mechanisms underlying melanonychia are not fully understood but may involve nail matrix or toxicity, stimulation of nail-matrix melanocytes, or drug deposition within the nail plate. This case highlights the possibility of dasatinib-induced transverse melanonychia and underscores the importance of monitoring and evaluating nail changes in patients undergoing dasatinib treatment.