Primary cutaneous anaplastic large-cell lymphoma: A case report.

Rationale: Primary cutaneous anaplastic large-cell lymphoma (C-ALCL) is a rare cancer belonging to the group of primary T-cell lymphoproliferative diseases. C-ALCL is characterized by the presence of single or multiple ulcerated lesions on the skin's surface.

Patient Concerns: This is the case of a 73-year-old man who reported to the Clinic of Cranio-Maxillofacial and Oral Surgery and Implantology, Medical University of Warsaw, owing to a skin tumor in the right parotideomasseteric region, initially diagnosed as discoid lupus erythematosus. During treatment for discoid lupus erythematosus, biopsy was repeated because of significant disease progression and dynamic tumor growth. Histopathological examination revealed the presence of pilomatrix carcinoma (trichilemmal carcinoma). Because of the discrepancy between clinical and histopathological findings, the tumor specimen was submitted to another facility, wherein lymphoma infiltration by anaplastic large cells was found in the dermis and subcutaneous tissue.

Diagnosis: C-ALCL.

Interventions: The patient was transferred to the Lymphoid Tumours Clinic of the Maria Skłodowska Curie Memorial Cancer Centre and Institute of Oncology in Warsaw, where chemotherapy was initiated.

Outcomes: After 4 cycles of chemotherapy, a complete remission of skin lesions was achieved. During the 5-year follow-up, no recurrence occurred.

Lessons: C-ALCL is a rare type of cancer. Misdiagnosis can lead to inappropriate therapy and result in disease progression or unnecessary harm to the patient.