Clinical Anatomy 24:757–762 (2011)
ORIGINAL COMMUNICATION
Accessory Spleens at Autopsy NADIRE UNVER DOGAN,1* ISMIHAN ILKNUR UYSAL,1 SERAFETTIN DEMIRCI,2 KAMIL HAKAN DOGAN,2 AND GIRAY KOLCU2 1
2
Department of Anatomy, Selcuklu Medical School, Selcuk University, Konya, Turkey Department of Forensic Medicine, Meram Medical School, Selcuk University, Konya, Turkey
Accessory spleens (AS) may be formed during embryonic development when some of the cells from the developing spleen are deposited along the path from the midline, where the spleen forms, over to its final location on the left side of the abdomen. An accessory spleen is usually near the spleen’s hilum, but it may be embedded partly or wholly in the tail of the pancreas. The aim of this study was to investigate the incidence and distribution of AS during routine forensic autopsies. AS were investigated in 720 consecutive autopsy cases. Fifty-four AS were found in 48 (6.7%) cases. AS were found in hilum of the main spleen in 28 cases, the great omentum in 13 cases, the pancreas in 5 cases, and the pelvis in 2 cases. There were two AS in two cases and three AS in another two cases. Awareness of the possible presence of AS is important because when splenectomy is performed for some conditions such as immune thrombocytopenic purpura, failure to remove the AS may result in the failure of the condition to resolve. Additionally, during medical imaging, AS may be confused for enlarged lymph nodes or neoplastic growths. In conclusion, autopsy series are useful for determining the incidences and the other features of AS in different populations, in addition to those studies using CT scans and those studies obtained during laparoscopic or open surgeries. Clin. Anat. 24:757–762, 2011. V 2011 Wiley-Liss, Inc. C
Key words: accessory spleen; anatomy; spleen; autopsy
INTRODUCTION The spleen consists of a large encapsulated mass of vascular and lymphoid tissue situated in the upper left quadrant of the abdominal cavity between the fundus of the stomach and the diaphragm (Standring, 2005). It contacts the posterior wall of the stomach and is connected to the greater curvature by the gastrosplenic (gastrolienal) ligament and to the left kidney by the splenorenal (lienorenal) ligament (Moore, 1992). The spleen appears at approximately the sixth week of embryologic life as a localized thickening of the coelomic epithelium of the dorsal mesogastrium near its cranial end. The proliferating cells invade the underlying angiogenetic mesenchyme, which becomes condensed and vascularized. The process occurs simultaneously in several adjoining areas, which soon fuse to form a lobulated spleen. In the subsequent C 2011 V
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periods of embryologic life, the earlier lobulated character of the spleen disappears but is indicated by the presence of notches on its upper border in the adult. The spleen can display various developmental anomalies, including complete agenesis, multiple spleens or polysplenia, isolated small additional splenunculi, and persistent lobulation (Standring, 2005). Accessory spleens (AS) may be formed during embryonic development as ectopic or separated splenic tissue along the path from where the spleen *Correspondence to: Dr. Nadire Unver Dogan, Department of Anatomy, Selcuklu Medical Faculty, Selcuk University, 42075 Konya, Turkey. E-mail:
[email protected] Received 25 August 2010; Accepted 10 January 2011
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Published online 3 March 2011 in Wiley (wileyonlinelibrary.com). DOI 10.1002/ca.21146
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forms at the midline to the spleen’s final location on the left side of the abdomen (Moore and Persaud, 1993; Standring, 2005). The aim of this study was to investigate the incidence and distribution of AS during routine forensic autopsies.
MATERIALS AND METHODS Prior to beginning this prospective study, forms were prepared to collect data about AS. Data was collected from 720 consecutive Anatolian medicolegal autopsies performed by forensic pathologists between 2005 and 2007 at The Konya Branch of Forensic Medicine Council (Turkey) and in the districts of Konya. While they were examining the specimens for disposition of the structures and organs of the abdomen, these same forensic pathologists (S.D. and K.H.D.) looked for accessory spleens in the abdomen. Sites examined for the appearance of accessory spleens were in the hilum of the main spleen, the tail of the pancreas, greater omentum, and in the pelvis. If accessory spleens were found, the prepared forms were filled out for each of the cases. The cases of AS were evaluated in terms of their demographic features, localization, number, shape (round, ovoid, triangular), and size (greatest diameter). None of the cases had any hematologic disorders or splenomegaly. None of the subjects had undergone a splenectomy or other surgery that might possibly damage the spleen and none of them had a history of trauma to the main spleen.
RESULTS Incidence and Demographic Features Fifty-four AS were found in 48 (6.7%) cases. These cases were aged from 3 months to 62 years and the ratio of males to females was 1.5:1. There was one AS in 44 cases, two AS in 2 cases and three AS in another 2 cases.
Localization The distribution of the 54 total AS is given in Figure 1. Twenty-eight (51.9%) of the AS were found near the hilum of the main spleen, 13 (24.1%) of them in the greater omentum (Fig. 2), 5 (9.3%) of them within the tail of the pancreas (Figs. 3 and 4), 3 (5.5%) of them in the gastrosplenic ligament (Fig. 4), 3 (5.5%) of them in the splenorenal ligament, and 2 (3.7%) of them in the pelvis (Fig. 5).
Shape and Size Forty-four (81.5%) AS were round, eight (14.8%) were ovoid, and two (3.7%) were triangular in shape. The greatest diameter of the AS ranged between 0.5 and 2.8 cm, and the mean greatest diameter was 1.6 cm.
Fig. 1.
The distribution of accessory spleens (n ¼ 54).
DISCUSSION AS are also known as ‘‘splenules’’ or ‘‘splenunculi.’’ Many authors reported an incidence rate between 10 and 30% especially in patients undergoing splenectomy for hematologic diseases (Halpert and Gyorkey, 1959; Beahrs and Stephens, 1980; Dodds et al., 1990; Freeman et al., 1993; Brunt et al., 1996; Glasgow et al., 1997). Park et al. (1999) reported an incidence rate of 15.0% for AS in patients undergoing laparoscopic splenectomy for different hematologic diseases. The largest series of CT studies was performed by Mortele ´ et al. (2004). They used contrastenhanced CT imaging and they reported that a 2-mm size accessory spleen can be determined by contrastenhanced CT. There is a lack of prospective consecutive autopsy series studies for determining the incidence of AS in different populations in the literature. In this study, the rate of AS was 6.7% within the incidence range (4.0–15.6%) reported in the literature published in the last 15 years which were performed by open and laparoscopic surgery, CT scans, or fetus dissections (Table 1). The reported frequencies for one, two and three AS have been reported as 79–86%, 10.5–14%, and 1–10.5%, respectively (Mortele ´ et al., 2004; Mendi et al., 2006; Ungo ¨r et al., 2007). In this study, one accessory spleen was the most common (91.6%), consistent with the literature. AS are usually near the spleen’s hilum, but they may be embedded partly or wholly in the tail of the pancreas (Moore, 1992), in the greater omentum (Standring, 2005), in the wall of the stomach or bowel, in the mesentery or even in the pelvis and scrotum (Sty and Conway, 1985; Hayward et al., 1992; Moore, 1992; Gayer et al., 2001; Standring, 2005). They are usually about 1 cm in diameter but vary from microscopic deposits not visible on
Accessory Spleens at Autopsy
Fig. 2. An accessory spleen (:) in the greater omentum in a 25-year-old woman. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
Fig. 3. An accessory spleen (:) embedded in the tail of the pancreas in a 32year-old man. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
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Fig. 4. Two accessory spleens (:) in a 3-year-old girl. One of them is embedded in the tail of the pancreas, the other one is in the gastrosplenic ligament. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
Fig. 5. An accessory spleen (:) in the pelvis in a 36-year-old woman. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
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TABLE 1. The Incidence of AS in Different Studies Author Yee et al. (1995) Winde et al. (1996) Park et al. (1999) Mortele ´ et al. (2004) Casaccia et al. (2006) Ungo ¨r et al. (2007) This study
Country
No. of cases
Method
Incidence (%)
USA Germany USA Belgium Italy Turkey Turkey
25 72 147 1,000 309 141 720
Laparoscopic surgery Open surgery Laparoscopic surgery CT scans Laparoscopic surgery Fetus dissections Autopsy cases
4.0 4.2 15.0 15.6 8.1 13.5 6.7
CT to 5 cm in diameter (Koehler, 1989; Moore, 1992; Moore and Persaud, 1993; Coote et al., 1999; Mendi et al., 2006). AS were found mostly (51.9%) near the hilum of the main spleen, and the greatest diameter of the AS ranged between 0.5 and 2.8 cm (mean greatest diameter, 1.6 cm) in this study. One of the most comprehensive studies about AS was performed by Mortele ´ et al. (2004) on abdominal contrast-enhanced CT scans of 1,000 consecutive patients. Of these patients, 156 (15.6%) had at least one accessory spleen, and 21 of these patients (13%) had more than one accessory spleen (two or three), resulting in a total of 180 AS. Their mean anteroposterior diameter was 11.9 mm. Their mean transverse diameter was 11.6 mm. The shape of AS was round in 141 patients (78.3%), ovoid in 27 (15%), and triangular in 12 (6.7%). The localization of AS in that study was variable. All of the AS were in the left upper quadrant of the abdomen and the most common localization was the inferior third of the posteromedial compartment of the left upper quadrant (21.8%). In two patients, intrapancreatic accessory spleen was found. However, they did not image the pelvis in their study population. In our study, there were five intrapancreatic AS and two intrapelvic AS. In addition, 81.5% of AS were round, 14.8% were ovoid, and 3.7% were triangular in shape, similar to the findings of Mortele ´ et al. The studies on AS have been generally performed on CT images of adult patients. In a study of fetal AS, Ungo ¨r et al. (2007) detected 25 AS in 19 (14%) of 141 fetuses. Of these 25 AS, 16 (64%) were located in the splenic hilum, 3 (12%) were in the gastrosplenic ligament, 3 (12%) were in the splenorenal ligament, 1 (4%) was near the pancreas tail, 1 (4%) was near the stomach, and 1 (4%) was in the great omentum. Similarly, most of the AS (51.9%) were in the splenic hilum in this study. Awareness of the presence of an accessory spleen is important in a patient evaluated by CT prior to splenectomy, as failure to remove it may result in persistence of the condition that indicated the need for splenectomy (Moore, 1992; Gayer et al., 2001). An accessory spleen may be of clinical importance as a source of ‘‘preservable’’ splenic tissue in cases of a ruptured primary spleen. Additionally, during medical imaging, AS may be confused for enlarged lymph nodes or neoplastic growths. An AS is an incidental finding of no clinical significance in most patients. AS are generally determined during radiological investigations or during open or laparoscopic surgeries (Yee et al., 1995). AS are usually asymptomatic, but they are rarely reported
to present clinically as an abdominal mass related to complications such as torsion, spontaneous rupture, hemorrhage, and cyst formation. Torsion and ischemia of AS can lead to gangrene, abscess, peritonitis, and can present as an acute abdomen, as seen in torsion of the main spleen (Valls et al., 1998; Coote et al., 1999; Padilla et al., 1999; Grinbaum et al., 2006; Mendi et al., 2006). The European Association of Endoscopic Surgery has recommended a routine search for AS intraoperatively along with preoperative CT scan to achieve the highest detection rates and to prevent disease recurrence, especially for autoimmune hematological disorders. However, the value of preoperative imaging to detect AS remains unclear (Quah et al., 2010). Some researchers report that the sensitivity of detecting AS with preoperative CT is higher (Gigot et al., 1998; Napoli et al., 2004), but others report that laparoscopy has a higher sensitivity (Stanek et al., 2005; Quah et al., 2010). Quah et al. (2010) recently reported that the sensitivity of CT scan before laparoscopic splenectomy in detecting AS was 60%, whereas the sensitivity of laparoscopy in detecting AS was 93%. It was also reported that Tc99m heat denatured red blood cell SPECT technique and reticuloendothelial system-specific contrastenhanced MRI may be used for detecting AS (Phom et al., 2001; Boraschi et al., 2005). During laparoscopic exploration, AS are routinely searched for in the splenic hilum, the great omentum, and the left paracolic space, as well as in the lienocolic, splenorenal, and gastrocolic ligaments; the lesser sac and the tail of the pancreas (Rudowski, 1985; Gigot et al., 1998). A handheld gamma probe is a useful and successful adjunct to localization and removal of AS (Bergeron et al., 2008). In this study, although the most common localizations of AS were the regions that are routinely searched to detect AS in laparoscopic splenectomy (96.3%), 3.7% of the AS were detected in the pelvis. As pelvis and scrotum are reported as localizations for AS, surgeons should keep these atypical localizations in mind.
CONCLUSION The incidence and morphological and morphometric features of AS in 720 consecutive Anatolian autopsy cases are evaluated in this prospective study. The most important limitation of this study was that the determination of AS in these autopsies was performed only macroscopically. In addition, AS in the scrotum could not be determined because the scro-
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tum was not dissected during routine autopsies. The localizations and the morphological and morphometric features of the AS were determined in detail, and the AS were photographed. It is concluded that, in addition to studies on CT scans and laparoscopic or open surgery series, autopsy series are useful for determining the incidences and the other features of AS in different populations.
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