Clinical and Radiographic Characteristics of Sinonasal Posttransplant Lymphoproliferative Disorder and Invasive Fungal Sinusitis.

<bold>Background: </bold>Sinonasal posttransplant lymphoproliferative disorder (PTLD) is a serious but uncommon complication of solid organ and hematopoietic stem cell transplantation that can overlap in many features with invasive fungal sinusitis (IFS).<bold>Objective: </bold>To identify clinical, laboratory, and radiographic features that may help to differentiate sinonasal IFS and PTLD in the posttransplant population.<bold>Methods: </bold>We performed a retrospective chart review of patients with posttransplant sinonasal PTLD and IFS to evaluate for clinical, laboratory, and imaging characteristics.<bold>Results: </bold>A total of 4 patients with sinonasal PTLD and 10 posttransplant IFS patients were evaluated. A total of 2 of 4 PTLD patients presented with a symptom duration of greater than 3 months compared to none in the IFS group (p = 0.07). Mean absolute neutrophil count (ANC) was 2,976 per mm3 (range 2,488-3,462) in the PTLD group compared to 773 per mm3 (range 0.0-2,744) in the IFS group (p = 0.01). Both PTLD lesions with available diffusion-weighted imaging demonstrated diffusion restriction on magnetic resonance im-aging (MRI) compared to zero of the IFS lesions (p = 0.10). No PTLD lesions demonstrated mucosal infarcts compared to three of seven IFS lesions (p = 0.23).<bold>Conclusion: </bold>IFS was associated with a significantly lower ANC at the time of diagnosis compared to PTLD. Additionally, three other measures trend towards association with their respective pathology. PTLD typically has a more chronic time course than IFS, diffusion restriction on MRI is predominantly associated with PTLD patients, and mucosal infarct on MRI is more suggestive of IFS. Additionally, all cases of sinonasal PTLD arose following solid organ transplantation. These factors may assist clinicians during diagnosis. [ABSTRACT FROM AUTHOR]