Because the neoplastic clone was CD20−, CD56−, CD138+, and cyclin D1+ with the absence of a somatic MYD88 L265P mutation and with a positivity for t(11,14), and in consideration of the patient’s clinical presentation (absence of adenopathy, organomegaly, and B-constitutional symptoms), a diagnosis of WM was unlikely, and IgM-κ MM was finally defined. Here, CD40LG is linked to Miyoshi myopathy.