Non-invasive evaluation of a liver mass in a patient post splenectomy

Introduction

Liver lesions are most commonly classified as solid or cystic based on radiographic appearance. The differential diagnosis of solid liver lesions is broad. Some of these lesions are benign, such as hepatic haemangioma, focal nodular hyperplasia, hepatic adenoma, idiopathic non-cirrhotic portal hypertension (including nodular regenerative hyperplasia) and regenerative nodules. However, malignancies may also feature, including hepatocellular carcinoma (HCC), cholangiocarcinoma and metastatic disease. ¹

The majority of patients with solid liver lesions are asymptomatic. However, some may have symptoms or findings related to the lesion (e.g. pain, jaundice or a palpable mass), or related to the primary cause of the lesions such as signs of metastatic tumour elsewhere, or general symptoms such as weight loss. ²

In many cases, the diagnosis can be made with a combination of history, physical examination, laboratory testing and imaging studies. Trozilli et al. suggested in 1999 that the diagnosis can usually be made conservatively. This group evaluated 160 consecutive patients with focal liver lesions where malignancy could not be excluded, and operation was scheduled. Evaluation included imaging studies and laboratory tests, including tumour markers. Liver biopsy was not done in any patient. All patients subsequently underwent surgical excision. Preoperative diagnosis was correct in 221 of the 225 focal lesions assessed (98%). ³ Two decades after this publication, conservative diagnosis is at least as accurate as then. However, Trozilli et al. did not describe patients with splenosis and whether it can be diagnosed conservatively.

Here we present a rare cause of intrahepatic mass that was diagnosed non-invasively and treated conservatively.

Case presentation

A 35-year-old man complained of vague abdominal pain for four months. The pain was diffuse, more severe in right upper quadrant, and was not related to food, but was accompanied by nausea, without vomiting or diarrhoea. The patient denied any fever, weight loss, alcohol or drug use, or family history of malignancies.

His medical history did not include any chronic diseases or chronic use of medications.

Twelve years before, after a motor vehicle accident, he had undergone exploratory laparotomy and splenectomy because of grade V spleen laceration.

On physical examination, he looked well, and vital signs were normal. The abdomen was soft, with no tenderness. The rest of the physical examination was unremarkable.

Laboratory tests showed no abnormalities in full blood count, liver enzymes, albumin, bilirubin or the international normalised ratio.

Trans-abdominal sonogram revealed two slightly hyperechoic liver lesions measuring 43 mm and 35 mm in diameter (Figure 1). A subsequent contrast-enhanced tri-phasic computed tomography showed multiple oblong, subcapsular liver lesions with maximal diameter of 3 cm. The lesions were isointense in the non-contrast scan (Figure 2(a)), inhomogeneously hyperdense in the arterial phase (Figure 2(b)) and iso- to mildly hypointense in the portal (Figure 2(c)) and late phases (Figure 2(d)). OPEN IN VIEWER

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Figure 2.

CT of the liver shows multiple isodense lesion in the non-contrast scan (a), hyper enhancement in the arterial phase (b) and iso- to hypoenhancement in the portal (c) and late (d) phases of the scan (arrows).

This pattern of enhancement does not fit for a haemangioma but is frequently seen in hypervascular liver lesions such as adenoma or focal nodular hyperplasia. Carcinoma could not be ruled out. Liver metastasis was highly unlikely in a young patient with no clinical signs, risk factors or any hint of primary malignancy in abdominal CT. However, the multiplicity of the lesions, the predominantly subcapsular location, combined with the history of splenic trauma and splenectomy raised the suspicion of the rare diagnosis of liver splenosis. Liver biopsy was considered, but in view of the high risk for bleeding in a case of haemangioma or splenic tissue, this procedure was not performed.

Tc-99m-labelled heat-denaturated red blood cell scintigraphy was suggested to confirm this diagnosis. The rationale of the scan is that the heat-damaged erythrocytes are sequestered by reticuloendotelial cells and can be used to identify splenic tissue. The examination was performed and revealed several areas of increased subcapsular absorption of labelled red cells in the right lobe of liver, in the left upper abdomen and right pelvis (Figure 3). The finding was compatible with intrahepatic and intraabdominal splenosis which most probably occurred as one of the sequelae of abdominal trauma at the time of the road accident. OPEN IN VIEWER

After making the diagnosis based on clinical and imaging studies, further evaluation via biopsy seemed redundant, and a decision was made to manage the patient conservatively. Indeed, after 18 months of follow-up, the patient's condition is stable, without weight loss or any other sign of clinical deterioration. The abdominal pain has not changed (the diagnosis of splenosis may, or may not, be incidental) and is relieved by painkillers.

Discussion

Splenosis is a benign condition most commonly resulting from traumatic splenic rupture or splenectomy. ⁴ There are usually multiple auto-implantations of splenic fragments onto serosal surfaces of the intestine and mesentery, the omentum, the diaphragm and/or the pelvis. ⁵ In the vast majority of cases, patients are asymptomatic. Non-specific symptoms such as abdominal pain or diarrhoea may lead to the diagnosis. Gastrointestinal bleeding after rupture of a splenic implant nodule and intestinal obstruction are rather rare complications. ⁶

Splenosis is estimated to occur in about 67% of cases of traumatic spleen rupture. However, intrahepatic splenosis is a rare complication. ⁷ This condition can be confused with various hypervascular benign or malignant liver tumours such as hepatic adenoma, focal nodular hyperplasia, lymphoma, and haemangioma and HCC. ⁷ If splenosis is suspected – either clinically or radiographically – radionuclide scintigraphy can be used to confirm the diagnosis. ⁸

The radiological findings in intrahepatic splenosis by standard imaging techniques, such as ultrasonography, CT or MRI, are usually non-specific. On ultrasound, it can be hypo-, iso- or hyperechoic. ⁸ The CT or MRI enhancement pattern is compatible with other more common vascular lesions such as hepatic adenoma, focal nodular hyperplasia, haemangioma, HCC or metastatic liver neoplasms. ⁹

The differential diagnosis of splenosis is wide and includes both benign and malignant entities. In the majority of published case reports, the final diagnosis was made by liver biopsy or surgical exploration. Of 22 cases we found on Pubmed, in 19, the diagnosis was made histologically. Only in three cases was the diagnosis based on imaging findings; one of which after a non-specific histological picture was reported.

Tc-99m-labelled heat-denatured erythrocyte scintigraphy (Tc-99m-Pyperythrocyte SPECT) is based on the finding that functioning splenic tissue will trap approximately 90% of damaged erythrocytes, which allows the diagnosis to be confirmed (Figure 3). ¹⁰ This is a non-invasive procedure that avoids biopsies or surgical resections that might entail a high risk of complications, especially bleeding. ¹¹ Although the exact sensitivity and specificity of this test is yet to be determined, it is considered the procedure of choice to diagnose ectopic spleen tissue. ¹¹ Moreover, this test is thought to be superior to MRI and CT: Horger et al. compared CT and MRI to Tc-99m-Pyperythrocyte SPECT in patients with suspected ectopic spleen tissue, while the final diagnosis was based on pathology, and showed that Tc-99m-Pyperythrocyte SPECT is more sensitive and specific than CT and MRI. ¹²

Since this splenic tissue may be partially or fully functioning, it may have some beneficial immune function for the patient; indeed, the management of this entity should be conservative. ¹³

Conclusion

The diagnosis of intrahepatic splenosis should be taken into consideration in patients with a history of abdominal trauma who present with an indeterminate focal liver lesion. The use of Tc-99m-labelled heat-denatured erythrocyte scintigraphy (Tc-99m-Pyperythrocyte SPECT) is considered as the technique of choice. This has been shown in instances of atopic spleen tissue in different locations.^14–16 The same is true in intrahepatic splenosis.^11,14,17 In summary, we recommend non-invasive investigation including (Tc-99m-Pyperythrocyte SPECT) to investigate intrahepatic liver lesion suspected for splenosis. This may obviate the need for liver biopsy and its inherent dangers.