A case of primary cutaneous diffuse large B-cell lymphoma, leg type with MYC rearrangement and high BCL2 protein expression due to trisomy 18.

We report the case of an 80-year-old woman with a medial thigh nodule who was diagnosed with primary cutaneous diffuse large B-cell lymphoma, leg type. Further examination identified it as double-expressor lymphoma with elevated expression of both MYC and BCL2. This elevated expression has been linked to MYC translocation and is likely associated with trisomy 18. Our findings suggest that trisomy 18 plays a significant role in the development of double-expressor lymphoma. While cases of double-expressor lymphoma caused by extra copies of BCL2 have been reported, we could not find any case of double-expressor lymphoma caused by trisomy 18. Therefore, this is an unique case of double-expressor lymphoma linked to MYC rearrangement and trisomy 18. Double-expressor lymphoma typically has a poor prognosis and is often resistant to standard treatments. The current findings may help refine diagnostic strategies for this condition.