Recognizing seromadesis to prevent false-positive PET-CT interpretations.

Abstract

e22084 Background: Seromas are the result of a local inflammatory response to a mechanical injury incurred by tissue aggression either during surgery or the presence of foreign bodies. Unfortunately, the common practice of using of percutaneous or surgical drains, does not decrease the frequency of seroma formation and is associated with an increased risk of infection. Methods: Since first introduced in 1935 for pleurodesis, talcum powder has been used extensively as a simple, effective, and economic procedure for the treatment and prophylaxis of recurrent pleural effusions. It induces a strong fibrotic reaction due to the activation of polymorphonuclear neutrophils, interleukin 8 and fibroblast growth factor. One of the earliest documented uses was by Coons et al., in 1993 utilizing an experimental dog model. In 2006, Saeb-Parsy et al. described its use in recurrent seroma after breast surgery. More recently in 2012, Klima et al. reported that a prophylactic application of subcutaneous talc after axillary dissection in a porcine model safely reduces drain duration and prevents seromas without local or systemic side effects. More recently, it has also been used in superficial soft tissue excisions for melanomas and large metastatic lymphadenopathy excisions. Currently, F-18 FDG PET-CT is widely used in the diagnosis and management of patients with malignancies. However, the imaging tracer F-18 FDG is utilized not only by malignant cells but by infectious, inflammatory cells as well resulting in false ‘positive’ findings. Results: When a patient undergoes pleurodesis using talc, the local inflammatory process is seen as intense increased F18 FDG activity on PET-CT scan. This can be perceived and misinterpreted as initial or recurrent malignant foci or infection. Thus it is imperative that interpreting physicians be aware of the wide range of application of talcum powder to any site with a potential of seroma development. Conclusions: Presence of intense F-18 FDG activity corresponding to somewhat linear irregular area of hyperdensity seen in the CT portion of PET-CT in previous surgical bed should alert the interpreting physician on strong probability of talc induced exuberant inflammatory reaction and associated F-18 FDG activity.