Letter from the Guest Editor

Article Outline

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The spleen has traditionally been regarded as an ‘orphan’ organ. Although its embryological development is usually described together with that of the digestive system, it is not a part of the gastrointestinal tract. Functionally, the spleen comprises the largest mass of lymphoid tissue in the body. Its important hematopoietic functions in early fetal development, producing both red and white blood cells, are usually lost in a later stage of fetal life. Nevertheless, the spleen continues to act as a sophisticated filter; it manages and monitors blood cell functions and has also important immune functions.

Since the spleen is not necessary for the preservation of vital life functions, the organ receives limited attention by both radiologists and clinicians. It can, however, be affected by a wide range of pathologic conditions. In the early stages of preparing this issue I had hoped to come up with six topics that would cover the spectrum of pathological processes affecting the spleen. After plunging into the ocean of PubMed data, however, it suddenly seemed impossible to squeeze all the relevant topics into only one issue without leaving out several exciting ones. I therefore decided to take this opportunity and honor the spleen with two issues, the present one and the second one to be published in February 2007.

The current issue opens with a review of congenital anomalies of the spleen. Some anomalies are common and often of no clinical significance (e.g. accessory spleen), yet others are very rare (wandering spleen and polysplenia) and pose intriguing diagnostic challenges, when not acquainted with them. The diagnosis of a congenital splenic anomaly is not only an intellectual exercise but may have crucial clinical implications, such as torsion of a wandering spleen, which presents as an acute abdomen.

The next two reviews focus on acquired splenic lesions and have been divided for the sake of clarity into two comprehensive articles. The first one is a superb exploration of solitary splenic lesions by David Warshauer and Lee Hall from the University of North Carolina School of Medicine. Many splendid illustrations show the entire spectrum of both common and rare lesions, further divided didactically into predominantly cystic and solid lesions. The second review, focusing on multiple lesions of the spleen, is an outstanding pictorial essay by Terry Desser and her associates from Stanford University School of Medicine. The article covers the gamut of abnormalities that may manifest as multifocal splenic lesions and discusses the challenge for the radiologist in distinguishing ominous lesions from innocuous ones.

Next, we concentrate on trauma, as the spleen is the organ most often injured in blunt abdominal trauma. CT has revolutionized the management of splenic injury. Prior to the use of CT in diagnosing abdominal injuries it was assumed that an injured spleen invariably continued bleeding unless treated. The incidental CT observations of a damaged spleen in stable patients ushered in the era of non-operative management. Helen Marmery and Kathirkamanathan Shanmuganathan from University of Maryland Medical Center, Baltimore provide an excellent review highlighting the crucial role of CT in the evaluation of the hemodynamically stable patient with blunt abdominal trauma.

The last two articles illuminate new technologies applied in the evaluation of the spleen. Characterizing solid splenic lesions as benign or malignant may be problematic with US, CT and MRI due to overlap in imaging features. 18F-FDG-PET/CT is an emerging non-invasive imaging modality that may play an important role in distinguishing between benign and malignant solid splenic lesions. This differentiation is very important because it might save splenic biopsy, which although feasible, is not without risk. Ur Metser and Einat Even-Sapir, from the Tel-Aviv University in Israel, elucidate the role of 18F-FDG PET/CT in the evaluation of solid splenic masses in a well-written review. The last article highlights the value of low-mechanical index, contrast-enhanced ultrasonography, a relatively new technique allowing real-time, gray-scale imaging during microbubble contrast medium circulation. Orlando Catalano and his colleagues from the National Cancer Institute Naples, Italy contribute an excellent review on the use of contrast ultrasonography in the evaluation of the spleen, a most suitable organ for applying this modality.

After all these wonderful reviews covering the spleen from various aspects, you might wonder what else is there to know about the spleen and what the second issue will contain. In short, it will include reviews on specific diseases affecting the spleen, such as lymphoma, sarcoidosis and hydatidosis, on vascular pathology of the spleen, on postsplenectomy complications, on percutaneous invasive splenic procedures and a few surprises.

I extend my sincere thanks to all the authors for their fine reviews and hope this issue on the spleen provides a very useful reference in daily practice.