Eur Radiol (2002) 12:S62–S65 DOI 10.1007/s00330-002-1561-5
Zekai Pekkafalı A. Fevzi Karslı Emir S¸ilit C. Çınar Bas¸ekim Yavuz Narin Hakan Mutlu Es¸ref Kızılkaya
Received: 28 September 2001 Revised: 14 May 2002 Accepted: 4 June 2002 Published online: 29 August 2002 © Springer-Verlag 2002 Z. Pekkafalı (✉) · A.F. Karslı · E. S¸ilit C.Ç. Bas¸ekim · H. Mutlu · E. Kızılkaya Department of Radiology, GATA Haydarpas¸a Training Hospital, Kadıköy 81327, Istanbul, Turkey e-mail:
[email protected] Tel.: +90-216-3462600/2887 Fax: +90-216-3304389 Y. Narin Department of Nuclear Medicine, GATA Haydarpas¸a Training Hospital, Kadıköy 81327, Istanbul, Turkey
H E PAT O B I L I A R Y – PA N C R E A S
Intrahepatic splenosis: a case report
Abstract Splenosis is heterotopic autotransplantation and seeding of splenic tissue. In the literature, only a few cases of splenosis involving the liver and the radiologic characteristics of these lesions have been reported. We report a case of intrahepatic splenosis diagnosed by ultrasound, computed tomography, magnetic resonance imaging and scintigraphic features. To our knowledge, our patient is the first case diagnosed only by radiologic and radionuclide examination without any intervention.
Keywords Intrahepatic splenosis · US · CT · MRI · Heat-damaged red blood cell (RBC) scintigraphy · Liver neoplasms
Introduction
Case report
Splenosis represents heterotopic autotransplantation and seeding of splenic tissue, usually occurring after splenic trauma or surgery [1, 2, 3, 4]. Splenic seeds may be situated anywhere within the peritoneal cavity, but they usually take place on the serosal surface of the small and large intestine, the parietal peritoneum, the mesentery, and the diaphragm [1, 2, 3, 4]. In the literature, only a few cases of splenosis involving the liver and the radiologic characteristics of these lesions have been reported [1, 2, 5]. We report a patient in whom the diagnosis of intrahepatic splenosis, occurring after previous trauma and splenectomy, was suggested by US, CT, and MRI findings. The diagnosis was confirmed by radionuclide imaging.
A 21-year-old man was seen in February 2001 because of epigastric pain. The medical history was characterized by an upper abdominal trauma with splenic rupture, for which splenectomy had been performed after an automobile accident 15 years previously. The results of physical examination were unremarkable. Laboratory test results were within normal limits. Sonography showed a highly homogeneous, hypoechoic solid mass with enhanced through-transmission, measuring 34×23 mm in dimension, situated in the left hepatic lobe (Fig. 1). The lesion revealed nonspecific arterial and venous color Doppler signals. Noncontrast CT scan of abdomen showed this mass as well demarcated and slightly hypodense with prominent hypodense rim around the lesion (Fig. 2A). After contrast administration, the lesion was hyperdense in the arterial phase, isodense in the portal venous phase (Fig. 2B), and hypodense in the equilibrium phase. Magnetic resonance imaging of the abdomen was performed at 1.5 T with spin-echo and gradient-echo pulse sequences, before and after IV administration of gadopentetate dimeglumine. Precontrast MRI showed that this lesion was homogeneously hypointense on T1-weighted image (Fig. 3A) with TR=174.9 ms and
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TE=4.1 ms and isointense to liver with a thin hypointense rim around the lesion on fat-suppressed T2-weighted image with TR=4952 ms and TE=99 ms (Fig. 3B). The lesion was hyperintense to liver on postcontrast MR image (Fig. 3C). T1- and T2-weighted appearances of hypointense rim suggest the presence of a thin fat or fibrous capsule around the lesion.
Based on a history of previous splenectomy that was a major clue for the diagnosis of intrahepatic splenosis, and with these nonspecific imaging features, the patient was referred to radionuclide scintigraphy to confirm the diagnosis. Heat-damaged red blood cell (RBC) scintigraphy performed with 2 mCi (37 MBq) 99m technetium (Tc)-labelled autologous RBCs and showed uptake of the labelled cells in areas corresponding to the mass seen on US, CT, and MRI (Fig. 4).
Discussion
Fig. 1 Sonogram shows a well-circumscribed, homogeneous, hypoechoic liver lesion located in the left hepatic lobe. Note the enhanced through-transmission in a solid structure
Splenosis is implantation of splenic tissue after splenic trauma or splenectomy [5]. Because splenosis is usually an incidental finding at surgery and autopsy, the true incidence is unknown [1, 2, 3, 4, 5, 6]. Actually all patients have a history of either splenic trauma or splenectomy, during which the splenic pulp is implanted throughout the peritoneal cavity [1, 2, 3]. Hematogenous spread of splenic pulp has also been depicted as a possible mechanism of seeding into the liver [3]. The implants may be situated anywhere in the peritoneal cavity. Intrathoracic and subcutaneous locations and implants within the pleural cavity or pericardium have been defined after pene-
Fig. 2 A Precontrast CT scan of abdomen reveals this mass as well demarcated and slightly hypodense with prominent hypodense rim around the lesion. B Contrast-enhanced CT image depicts the lesion as isodense in the portal venous phase
Fig. 3 A Precontrast T1-weighted MR image delineates the lesions as an homogeneously hypointense mass. B Fat-saturated T2-weighted image shows the lesion as well-circumscribed, ho-
mogeneous, isointense to liver with a thin hypointense rim around the lesion. C Postcontrast MR image reveals the lesion as a wellcircumscribed, homogeneously enhancing hepatic mass
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Fig. 4 Heat-damaged and Tc-99 m-labelled autologous red blood cell scintigram shows uptake of the labelled cells in areas corresponding to the masses seen on US, CT, and MRI (arrow)
trating abdominal trauma [3, 7, 8]. Intrahepatic splenosis rarely causes symptoms. Some lesions, however, can cause abdominal pain by twisting of a long pedicle attached to the splenic nodule [4, 6]. Recurrence of Felty’s syndrome has also been reported as a complication of splenosis because splenic implants resume splenic function in 1–3 months [3, 6]. Intestinal obstruction related to splenic implants may take place [3]. In the literature, radiologic characteristics of normal splenic tissue were considered nonspecific. The MRI appearance of normal splenic tissue has rarely been defined. According to Adler et al. [9], the normal spleen is hyperintense with respect to liver tissue on T2-weighted images. We think that the similarity between radiologic appearance of the lesion and the normal splenic tissue is the most important imaging feature in the cases with splenosis. In our case, US, CT, and MRI appearances of the ectopic splenic tissue were in accord with true splenic tissue. To our knowledge, there are only two previously reported cases of intrahepatic splenosis involved almost at the same location in the liver in patients who have undergone splenectomy. In the first case, this specific location has been described in invagination of the parietal peritoneum within the falciform ligament, as a site of splenosis implantation first by Gruen and Gollub, with US and CT appearances [1]. In the other case, reported by DeVuysere et al., the larger lesion with, additionally, two smaller splenosis implantations has been presented by US, CT, and MRI uptake of small iron oxide particle features at the similar location [5]. In our case, the lesion was seen as in this specific location, a highly homogeneous, hypoechoic solid structure with enhanced through-transmission in sonography. Enhanced through-transmission is an interesting sono-
graphic feature in a solid lesion, which was also previously reported in the first case [1]. This feature may result from the differences between the acoustic impedance of liver and splenic tissue. Noncontrast and postcontrast CT scans showed the lesion slightly with different density values with respect to surrounding the liver tissue with prominent hypodense rim around the lesion. The MRI characteristics may suggest that the diagnosis was determined by the signal intensities on T1- and T2-weighted images, contrast enhancement of the lesion, and the presence of a thin rim surrounding the lesion. In this case, US, CT, and MRI appearances of the lesion were compatible with those of other cases mentioned above [1, 2]. For us, from all these characteristics of the lesion, the most interesting imaging feature is the presence of prominent surrounding rim. This rim was hypodense on CT and hypointense on all sequences of MRI, as in the previously reported cases. T1- and T2-weighted appearances of hypointense rim suggest the presence of a thin fat or fibrous capsule around the lesion. Although we do not have the pathologic proof, this rim also implies that the lesion was surrounded by invaginated parietal peritoneum. However, all these features were not specific and almost indistinguishable from those of the other hepatic tumors. With only these imaging features, it is difficult to distinguish splenosis implantation from other hepatic masses such as adenoma, focal nodular hyperplasia, and atypical form of hepatocellular carcinoma and hemangioma. The similarity between radiologic appearances of the lesion and the normal splenic tissue, and peripheric rim surrounding the lesion, suggests that the specific location of the mass depends on an invagination of the parietal peritoneum explained as a site of splenosis implantation. The rim would be quite unusual for a primary liver lesion such as focal nodular hyperplasia or adenoma. This is a case of a patient in whom the diagnosis of intrahepatic splenosis occurred after previous splenectomy had been suggested as a result of a constellation of radiologic findings. Awareness of these imaging characteristics may obviate the use of surgical interventions to reach the correct diagnosis of these rare liver lesions. With these imaging features and based on a history of previous splenectomy that was a major clue for the diagnosis of intrahepatic splenosis, we referred the patient to radionuclide scintigraphy to confirm the diagnosis. The scintigraphic feature of splenosis is uptake of technetium (Tc)-99 m-labelled heat-damaged red blood cells (RBC) in the areas of suspected heterotopic splenic tissue. In our case, heat-damaged and Tc-99 m-labelled autologous RBC scintigram showed uptake of the labelled cells in area corresponding to the mass seen on US, CT, and MRI. Because functioning splenic tissue will trap approximately 90% of damaged erythrocytes, Tc-99 m-labelled heat-damaged RBCs are reported to be more sensitive than
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sulfur colloid in the identification of splenosis. Labelled RBC studies may be particularly useful in the settings of minimal splenic tissue, poor splenic uptake, or overlap of the liver and spleen on sulfur colloid imaging [10]. In all of the cases with intrahepatic splenosis previously reported in the literature, the radiologic features were almost the same, as in our case. In these cases, despite the RBC scintigraphy, the gold standard for diagnosis of splenosis implantation, it had not been applied, and surgical biopsy or resection were needed to reach the
correct diagnosis [1, 2, 5]. In the current case, we omitted invasive and useless interventions, such as biopsy, angiography, and operation, to confirm the diagnosis. To our knowledge, this patient is the first case of intrahepatic splenosis in whom the diagnosis was confirmed preoperatively only by radionuclide scintigraphic examination. The Tc-99 m-labelled heat-damaged RBC scintigraphic imaging can confirm the diagnosis, preclude unnecessary interventional procedures, and prevent the potentially life-threatening risks of asplenia.
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4. Marchant LK, Levine MS, Furth EE (1995) Splenic implant in the jejunum: radiographic and pathologic findings. Abdom Imaging 20:518–520 5. DeVuysere S, Van Steenbergen W, Aerts R, Van Hauwaert H, Van Beckevoort D, Van Hoe L (2000) Intrahepatic splenosis: imaging features. Abdom Imaging 25:187–189 6. Bock DB, King BF, Hezmall HP, Oesterling JE (1991) Splenosis presenting as a left renal mass indistinguishable from renal cell carcinoma. J Urol 146:152–154 7. Grantham JR (1990) Subcutaneous splenosis. Am J Roentgenol 154:655
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