Follicular lymphoma (FL) often transforms to diffuse large B-cell lymphoma (DLBCL) during its protracted clinical course. Rarely, histiocytic sarcoma (HS) occurs secondary to or concurrent with FL, although the biological relationship between these 2 morphologically and immunophenotypically distinct entities in the same individual has not been well characterized. We report a unique case showing the sequential occurrence of first, HS and then DLBCL in a patient with a remote history of FL. In this case, HS developed 17 years after the diagnosis of FL and was shown to partly retain the immunophenotypic features characteristic of FL, while showing the morphologic and immunophenotypic profiles diagnostic of HS. DLBCL occurred 18.5 years after FL. Both HS and DLBCL harbored the IGH/BCL2 fusion gene, a hallmark of FL, per interphase fluorescence in situ hybridization analysis. Immunoglobulin gene rearrangement studies showed a clonal rearrangement of the IGH gene in both HS and DLBCL with identical amplicons, suggesting a shared origin of the neoplastic clones. These data support the hypothesis of transdifferentiation or transevolution in a mature B-cell neoplasm, and, in addition, suggest the possibility of a divergent (bilineal) neoplastic transformation of FL in a single individual.

Prostate cancer (PCa) is the most common non-cutaneous malignancy among men in the United States and the second leading cause of cancer-related death. Multi-parametric magnetic resonance imaging (mpMRI) has gained recent popularity to characterize PCa. Acoustic Radiation Force Impulse (ARFI) imaging has the potential to aid PCa diagnosis and management by using tissue stiffness to evaluate prostate zonal anatomy and lesions. MR and B-mode/ARFI in vivo imaging datasets were compared with one another and with gross pathology measurements made immediately after radical prostatectomy. Images were manually segmented in 3D Slicer to delineate the central gland (CG) and prostate capsule, and 3D models were rendered to evaluate zonal anatomy dimensions and volumes. Both imaging modalities showed good correlation between estimated organ volume and gross pathologic weights. Ultrasound and MR total prostate volumes were well correlated (R2 = 0.77), but B-mode images yielded prostate volumes that were larger (16.82% ± 22.45%) than MR images, due to overestimation of the lateral dimension (18.4% ± 13.9%), with less significant differences in the other dimensions (7.4% ± 17.6%, anterior-to-posterior, and −10.8% ± 13.9%, apex-to-base). ARFI and MR CG volumes were also well correlated (R2 = 0.85). CG volume differences were attributed to ARFI underestimation of the apex-to-base axis (−28.8% ± 9.4%) and ARFI overestimation of the lateral dimension (21.5% ± 14.3%). B-mode/ARFI imaging yielded prostate volumes and dimensions that were well correlated with MR T2-weighted image (T2WI) estimates, with biases in the lateral dimension due to poor contrast caused by extraprostatic fat. B-mode combined with ARFI imaging is a promising low-cost, portable, real-time modality that can complement mpMRI for PCa diagnosis, treatment planning, and management.

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