CD30⁺ extranodal natural killer/T-cell lymphoma mimicking phlegmonous myositis: A case report

The current study presents a case of a 23-year-old male with CD30⁺ nasal-type extranodal natural killer/T-cell lymphoma (NKTL), with unusual clinical features mimicking phlegmonous myositis. The patient initially presented with swelling and tenderness of the left lower limb, particularly around the left ankle. One month later, pharyngalgia and fever developed and the patient was treated with antibiotics for the phlegmonous inflammation, however, the symptoms were not relieved. A muscle biopsy was performed on the lesion and revealed diffuse infiltration of atypical lymphoid cells with irregular nuclei. Immunohistochemistry showed staining for CD3ɛ(-), CD20(-), CD45(+), CD30(+) and CD56(+) presented with positive staining for certain tumor cells, granzyme B(+), activin receptor-like kinase 1(-), Ki-67(+) and Epstein-Barr virus-encoded small RNA(+), which indicated nasal-type extranodal NKTL. The present case emphasized that extranodal NKTL may be a rare cause of phlegmonous inflammation and fever of undetermined origin.