82M history of RCC s/p radical nephrectomy many years ago, now with progressive pancytopenia, BMBx 6 months ago hypercellular with small B cell population (CD19, CD20, CD23) comprising <5%. All mutation testing negative and karyotype normal. Now having intermittent B symptoms. Over past 6 months has continued to be pancytopenia (WBC 2s, ANC 1-1.5, Hgb 8s, Plt 80s), but super large spleen measuring over 30cm, and recent PET demonstrated high activity in spleen (SUV 35) without any significant disease elsewhere. Only had some very small RP lymph nodes that lit up. Super high uric acid needing to be rasburicase twice in 1 week. But no other labs consistent with TLS (was actually hyperCa initially and needed denosumab). Spleen biopsy is nondiagnostic (necrotic tissue). I have a peripheral flow cytometry in-process. What is the possibilities and what would you do from here?
My thoughts: atypical Hairy cell leukemia (HCL-V), splenic marginal zone lymphoma, transformed aggressive B cell lymphoma primarily involving spleen?
Atypical HCL is my leading differential but it's just so rare..
Splenic marginal zone lymphoma is low grade and you wouldn't see such high FDG on PET (SUV 35 in spleen)
Transformed aggressive Bcell lymphoma would have obvious TLS and he should be having HypoCa (not hyperCa), hyperphos and hyperK, and elevated LDH, which he does not have any.
My thoughts on management:
1) can try and ask IR to repeat a spleen biopsy to see if they get viable tissue. I know spleen biopsies have high risk of bleeding
2) can see if a surgeon is willing to perform a splenectomy on this 82M with comorbidities. We would definitely get a tissue diagnosis if this is possible
3) treat with single agent rituximab and see what happens?
Thoughts?