MR imaging of the spleen: spectrum of abnormalities

Splenic sarcoidosis: a case report and review of the imaging findings of multiple incidental splenic lesions as the initial presentation of sarcoidosis

MRI is helpful in characterizing splenic lesions, but there can be significant variability and overlap in the appearance of both benign and malignant splenic lesions; thus, a confident diagnosis can be presentation and classic imaging appearance , and further assessment for any other associated findings suggestive of systemic sarcoidosis is critical to avoid missed or delayed diagnosis-specifically, to avoid over-diagnosis of malignant disease because multiple splenic lesions can be the initial presentation of sarcoidosis.

Endoscopic ultrasound guided fine-needle aspiration of a splenic hemangioma with extramedullary hematopoiesis

Extramedullary hematopoiesis (EMH) is the production of mature blood elements outside of the bone marrow and can occur as a compensatory result of a marrow replacing process or from marrow space occupying lesions such as tumor or marrow fibrosis. EMH can also be induced by factors elicited by neoplasms, such as vascular endothelial growth factor (VEGF). Usually, EMH is a diffuse process most commonly observed in lymph nodes, liver, and spleen. Rarely, EMH can form a mass lesion. Although the spleen is a common site for diffuse EMH, it is a rare location for a mass forming EMH. Hemangiomas are the most common benign tumors of the spleen. A case of a discrete, 8 cm lesion was noted incidentally on CT scan in a 59-year-old man with no significant past medical history. Endoscopic ultrasound guided fine-needle aspiration (EUS FNA) biopsy was performed and cytologic examination revealed trilinear hematopoiesis, with the most distinctive elements being megakaryocytes and erythroid precursors. A diagnosis of EMH was made. On resection, the mass was a hemangioma with EMH. EUS guided FNA is a useful tool for diagnosing splenic masses. Awareness of EMH, both as a mass forming lesion and a feature associated with benign and malignant vascular lesions is important, especially in patients with hematologic malignancies or marrow replacing processes.

Spleen in haematological malignancies: spectrum of imaging findings

Imaging morphology and metabolic activity of splenic lesions is of paramount importance in patients with haematological malignancies; it can alter tumour staging, treatment protocols and overall prognosis. CT, MRI and positron emission tomography (PET)/CT have been shown to be powerful tools for the non-invasive assessment of splenic involvement in various haematological malignancies. Since many haematological malignancies and non-neoplastic conditions can involve the spleen and imaging manifestations can overlap, imaging and clinical findings outside of the spleen should be looked for to narrow the differential diagnosis; confirmation can be obtained by pathological findings. Radiologists should be familiar with the cross-sectional imaging patterns of haematological malignancies involving the spleen as well as non-neoplastic splenic findings common in these patients to facilitate their care and follow-up. This pictorial review provides the common and uncommon imaging appearances and complications of various haematological malignancies involving the spleen on CT, MRI and PET/CT, and common pitfalls in diagnosis.

Unusual CT and MR Imaging Characteristics of Splenic Lymphoma

Lymphoma is the most common malignancy of the spleen. The imaging features of splenic lymphoma are nonspecific and mostly lymphomas present as a diffusely enlarged spleen. Focal lesions are described but remain of low density or intensity on CT or MRI, respectively. We describe a histologically proven case of splenic lymphoma that showed an atypical hyperdense/hyperenhancing appearance on imaging suspicious for a vascular pathology. To the best of our knowledge and based on review of English literature, such an appearance of splenic lymphoma is extremely unusual and rare.

How I diagnose and treat splenic lymphomas

The incidental finding of an isolated splenomegaly during clinical assessment of patients evaluated for unrelated causes has become increasingly frequent because of the widespread use of imaging. Therefore, the challenging approach to the differential diagnosis of spleen disorders has emerged as a rather common issue of clinical practice. A true diagnostic dilemma hides in distinguishing pathologic conditions primarily involving the spleen from those in which splenomegaly presents as an epiphenomenon of hepatic or systemic diseases. Among the causes of isolated splenomegaly, lymphoid malignancies account for a relevant, yet probably underestimated, number of cases. Splenic lymphomas constitute a wide and heterogeneous array of diseases, whose clinical behavior spans from indolent to highly aggressive. Such a clinical heterogeneity is paralleled by the high degree of biologic variation in the lymphoid populations from which they originate. Nevertheless, the presenting clinical, laboratory, and pathologic features of these diseases often display significant overlaps. In this manuscript, we present our approach to the diagnosis and treatment of these rare lymphomas, whose complexity has been so far determined by the lack of prospectively validated prognostic systems, treatment strategies, and response criteria.

Accessory spleen-like masses in oncology patients: Are they always benign?

AIM: To assess retrospectively the significance of accessory spleen-like mass (ASLM) in oncology patients undergoing positron emission tomography/computed tomography (PET/CT).

METHODS: The results of PET/CT of 913 patients (278 lymphoma; 635 solid tumors) were reviewed. The number, size, location and attenuation of all ASLMs, and spleen attenuation, were recorded. ASLM fluorodeoxyglucose uptake was graded as normal (less than or equal to that in the liver) or representative of malignancy (more than in the liver). Follow-up PET/CT in patients with ASLM was reviewed when available. ASLM size and attenuation for spleen and ASLM were compared by unpaired Student’s t test. The χ² and Fisher’s exact tests were used to compare ASLM frequency and uptake for lymphomatous and solid tumors, respectively.

RESULTS: ASLM frequency was 14.8%, with 152 ASLMs found in 135 patients. Mean attenuation was lower in ASLM compared with spleen by enhanced and non-enhanced CT (80.7 ± 20.4 HU vs 92.0 ± 14.4 HU, P < 0.0011 and 42.3 ± 9.0 HU vs 51.5 ± 6.3 HU, P < 0.0001, respectively). ASLM incidence was higher in lymphoma patients (56/278, 20.1%) than in those with solid tumors (56/278, 20.1% vs 79/635, 12.4%, P = 0.0036). Pathological uptake was found in four (7.1%) lymphoma patients but not in any patients with a solid tumor (P = 0.028) and it upstaged one patient with lymphoma. Follow-up PET/CT within 3-16 mo was available in 54% of patients with ASLM. Lesion regression was noted in all four pathological ASLMs on follow-up PET/CT after chemotherapy.

CONCLUSION: In patients with lymphoma, ASLM can represent malignancy, and thus further characterization with PET/CT might be warranted. Patients with neoplasia other than ASLM can be confidently diagnosed with accessory spleen.

Laparoscopic splenectomy for splenic hamartoma: Case management and clinical consequences

Splenic hamartoma is a rare benign tumor, and although minimally invasive surgery may be suitable for this condition, there have only been 2 previous reports of laparoscopic surgery. Here we report the third case of splenic hamartoma managed by laparoscopic splenectomy. A 37-year-old male was incidentally diagnosed by abdominal ultrasonography with a hypoechoic mass measuring 2.5 cm × 2.4 cm in the spleen. Color Doppler sonography showed multiple flow signals within the mass and contrast-enhanced computed tomography revealed strong enhancement of the lesion. On T1- and T2-weighted magnetic resonance images, the splenic mass was demonstrated as isointense and hyperintense respectively. Although a malignant tumor could not be ruled out, a hand-assisted laparoscopic splenectomy was performed because the splenic mass was limited in size and had not invaded adjacent organs. The pathological diagnosis was splenic hamartoma. The postoperative course was uneventful and the patient was discharged by the seventh postoperative day. Although splenic hamartomas have some specific imaging features, more reports and analyses of these cases are required to increase the reliability of the diagnosis and management. Hand-assisted laparoscopic splenectomy may play a pivotal role in the postoperative diagnosis and management of this condition.

Contrast-enhanced ultrasound with SonoVue: differentiation between benign and malignant focal liver lesions in 317 patients

PURPOSE

The aim of the study was to investigate the ability of contrast-enhanced sonography (CEUS) with the contrast agent SonoVue to differentiate between benign and malignant focal liver lesions.

METHODS

In a prospective study, we examined 317 patients (204 males, 113 females, aged 59 +/- 12 years) with focal liver lesions detected by B-mode gray-scale sonography. After intravenous injection of 1.2 mL SonoVue, the liver was examined continuously for 3 minutes using low-MI sonography with contrast-specific software. Final diagnosis was established by histopathology, CT, MRI, or HIDA-scintigraphy.

RESULTS

Two hundred nine patients had malignant focal lesions, including 107 hepatocellular carcinomas, 70 metastases, 26 cholangiocellular carcinomas, and 6 other types of malignancy. One hundred eight patients had benign focal lesions, including 30 regenerative nodules, 30 hemangiomas, 13 cases of focal nodular hyperplasia, 12 abscesses, 8 cases of necrosis, 7 cases of focal steatosis areas, and 8 other benign lesions. Hypoenhancement or no enhancement in the late phase was found in 91% of the malignant lesions but in only 37% of the benign lesions (p < 0.001, sensitivity = 64%, specificity = 93%). Hyperenhancement in the late phase was found in 20% of the benign lesions but in none of the malignant lesions (p < 0.001, sensitivity = 21%, specificity = 100%). Hyperenhancement in the early phase with diffuse complete enhancement was found in 30% of the patients with malignant lesions but in only 2% of the patients with benign lesions (p < 0.001, sensitivity = 30%, specificity = 98%). CEUS had a sensitivity of 90%, a specificity of 99%, and an accuracy of 89% in the diagnosis of malignant liver lesions.

CONCLUSION

CEUS is helpful in the differentiation between benign and malignant focal liver lesions.

Differentiation of benign from malignant focal splenic lesions using sulfur hexafluoride-filled microbubble contrast-enhanced pulse-inversion sonography

OBJECTIVE

The purpose of our study was to evaluate whether sonographic characterization of focal splenic lesions could be improved by using low mechanical index pulse-inversion sonography after sulfur hexafluoride-filled microbubble injection.

MATERIALS AND METHODS

One hundred forty-seven splenic lesions (68 benign, 79 malignant) in 147 patients (81 men, 66 women; mean age, 51 years) underwent baseline gray-scale sonography and sulfur hexafluoride-enhanced low-acoustic-power pulse-inversion sonography (mechanical index < 0.1). Two site investigators assessed in consensus lesion and splenic enhancement during arterial and parenchymal phases. Four readers (readers 1 and 2, blinded; and readers 3 and 4, unblinded to clinical data) independently reviewed baseline and contrast-enhanced sonograms and provided confidence rating for diagnosis of malignancy or benignancy. Accuracy, sensitivity, specificity, positive and negative predictive values, and areas under the receiver operating characteristic curves (A(z)) were calculated by considering biopsy results or splenectomy (51 patients) or CT or MR images followed by serial sonography 6-12 months apart (96 patients) as reference standards.

RESULTS

Benign lesions appeared predominately non- or isoenhancing relative to splenic parenchyma, whereas malignant lesions appeared predominately progressively hypoenhancing. For correct diagnosis of benignancy or malignancy, review of contrast-enhanced sonography after baseline sonography yielded significantly improved diagnostic performance (overall accuracy, 51%, 43%, 70%, and 74% before vs 83%, 81%, 92%, and 91% after contrast-enhanced sonography for readers 1, 2, 3, and 4; p < 0.05; respectively) and significantly improved diagnostic confidence (A(z), 0.770, 0.678, 0.900, and 0.917 before vs 0.935, 0.917, 0.984, and 0.959 after contrast-enhanced sonography for readers 1, 2, 3, and 4; p < 0.05; respectively).

CONCLUSION

Sulfur hexafluoride-filled microbubble-enhanced sonography improves characterization of focal splenic lesions with and without the availability of clinical data.

Contrast-enhanced ultrasonography with SonoVue: differentiation between benign and malignant lesions of the spleen

OBJECTIVE

We investigated the ability of contrast-enhanced ultrasonography with SonoVue (Bracco SpA, Milan, Italy), a sulfur hexafluoride microbubble contrast agent, to reveal differences between benign and malignant focal splenic lesions.

METHODS

In a prospective study we investigated 35 lesions in 35 patients (24 male and 11 female; mean age +/- SD, 54 +/- 15 years) with focal splenic lesions detected by B-mode ultrasonography. After intravenous injection of 1.2 to 2.4 mL of SonoVue, the spleen was examined continuously for 3 minutes using low-mechanical index ultrasonography with contrast-specific software. The final diagnosis was established by histologic examination, computed tomography, or magnetic resonance imaging.

RESULTS

In 14 patients, the splenic lesions were malignant (metastasis, n = 6; non-Hodgkin lymphoma, n = 6; and Hodgkin lymphoma, n = 2). In 21 patients, the focal splenic lesions were benign (ischemic lesion, n = 6; echogenic cyst, n = 5; abscess, n = 4; hemangioma, n = 3; hematoma, n = 1; hemophagocytosis syndrome, n = 1; and splenoma, n = 1. Typical findings for benign lesions were 2 arrival patterns: no contrast enhancement (neither in the early nor in the parenchymal phase; P < .05) and the beginning of contrast enhancement in the early phase followed by contrast enhancement in the parenchymal phase 60 seconds after injection. In contrast, the combination of contrast enhancement in the early phase followed by rapid wash-out and demarcation of the lesion without contrast enhancement in the parenchymal phase (60 seconds after injection) was typical for malignant lesions (P < .001).

CONCLUSIONS

Contrast-enhanced ultrasonography is helpful in the differentiation between benign and malignant lesions of the spleen.

Splenomegaly: investigation, diagnosis and management

Splenomegaly is a feature of a broad range of diseases, and presents to clinicians in many fields. This review examines the aetiology of splenomegaly in the developed world, and describes a logical approach to the patient with splenomegaly. In some patients, extensive radiological and laboratory investigations will fail to yield a diagnosis: these cases of "isolated" splenomegaly are not uncommon and can be particularly challenging to manage. The risks of serious underlying disease must be balanced against the risks of invasive investigations such as splenic biopsy and diagnostic splenectomy. We discuss the options in isolated splenomegaly and their evidence base, and incorporate them into a management strategy to aid the clinician in cases of diagnostic difficulty.

CT and MRI findings of sclerosing angiomatoid nodular transformation of the spleen: spoke wheel pattern

Sclerosing angiomatoid nodular transformation of the spleen is a recently described benign pathologic entity that is characterized by round shaped vascular spaces that are lined by endothelial cells, and the spaces are circumscribed by granulomatoid structures. Microscopically, all the reported cases had multiple angiomatoid nodules in a fibrosclerotic stroma. Each angiomatoid nodule was made up of slit-like, round or irregular shaped vascular spaces that were lined by endothelial cells and interspersed ovoid cells. We present here the CT and dynamic gadolinium-enhanced MR findings of a patient with sclerosing angiomatoid nodular transformation. The spoke-wheel pattern that was observed on MRI in this case may be an important imaging clue for making the correct diagnosis of this benign lesion.

Solitary littoral cell angioma of the spleen: computed tomography and magnetic resonance imaging features

Littoral cell angioma is a rare primary vascular neoplasm of the spleen composed of blood-filled vascular channels. Typically, littoral cell angioma presents with splenomegaly caused by multiple small hypoattenuating nodules that show delayed enhancement. We report an unusual case of littoral cell angioma of the spleen that presented as a large solitary mass.

Avaliação ultra-sonográfica de nódulos sideróticos esplênicos em pacientes esquistossomóticos com hipertensão portal

OBJETIVO: Medir a sensibilidade e a reprodutibilidade da ultra-sonografia na detecção de nódulos sideróticos esplênicos em pacientes esquistossomóticos, tendo a ressonância magnética como padrão de referência. MATERIAIS E MÉTODOS: Na primeira fase do trabalho, 21 pacientes portadores de esquistossomose na forma hepatoesplênica com diagnóstico de nódulos sideróticos à ressonância magnética foram submetidos a avaliação ultra-sonográfica para a determinação da sensibilidade do método. Na segunda fase, com o objetivo de avaliar a reprodutibilidade da ultra-sonografia na detecção e na quantificação de nódulos sideróticos (A: 1-5 nódulos; B: 6-20 nódulos; C: mais de 20 nódulos), outros 30 pacientes esquistossomóticos foram submetidos a avaliação ultra-sonográfica de forma cega e independente por dois observadores. A reprodutibilidade foi medida por meio da concordância entre os observadores e do teste kappa. RESULTADOS: A sensibilidade da ultra-sonografia foi de 95,2% (intervalo de confiança a 95% [77,3%; 99,2%]). A concordância entre ultra-sonografia e ressonância magnética para a detecção de nódulos sideróticos foi de 96,7% (intervalo de confiança a 95% [82,8%; 99,9%]). Para a classificação dos nódulos conforme a sua quantificação, o índice kappa demonstrou concordância interobservador substancial (kappa = 0,67). CONCLUSÃO: A ultra-sonografia é um método que apresenta elevada sensibilidade e boa precisão para a avaliação de nódulos sideróticos esplênicos.

Laparoscopic splenectomy: the clinical practice guidelines of the European Association for Endoscopic Surgery (EAES)

BACKGROUND

Although laparoscopic splenectomy (LS) has become the standard approach for most splenectomy cases, some areas still remain controversial. To date, the indications that preclude laparoscopic splenectomy are not clearly defined. In view of this, the European Association for Endoscopic Surgery (EAES) has developed clinical practice guidelines for LS.

METHODS

An international expert panel was invited to appraise the current literature and to develop evidence-based recommendations. A consensus development conference using a nominal group process convened in May 2007. Its recommendations were presented at the annual EAES congress in Athens, Greece, on 5 July 2007 for discussion and further input. After a further Delphi process between the experts, the final recommendations were agreed upon.

RESULTS

Laparoscopic splenectomy is indicated for most benign and malignant hematologic diseases independently of the patient's age and body weight. Preoperative investigation is recommended for obtaining information on spleen size and volume as well as the presence of accessory splenic tissue. Preoperative vaccination against meningococcal, pneumococcal, and Haemophilus influenzae type B infections is recommended in elective cases. Perioperative anticoagulant prophylaxis with subcutaneous heparin should be administered to all patients and prolonged anticoagulant prophylaxis to high-risk patients. The choice of approach (supine [anterior], semilateral or lateral) is left to the surgeon's preference and concomitant conditions. In cases of massive splenomegaly, the hand-assisted technique should be considered to avoid conversion to open surgery and to reduce complication rates. The expert panel still considered portal hypertension and major medical comorbidities as contraindications to LS.

CONCLUSION

Despite a lack of level 1 evidence, LS is a safe and advantageous procedure in experienced hands that has displaced open surgery for almost all indications. To support the clinical evidence, further randomized controlled trials on different issues are mandatory.

Vascular disease of the spleen

A wide range of vascular disorders can affect the spleen. Although clinical presentation is often nonspecific, early diagnosis and treatment are mandatory in most conditions. Noninvasive imaging techniques are well suited to meet these objectives. Familiarity with normal macroscopic and microscopic vascular anatomy is a prerequisite to understand the pathophysiology of vascular disorders of the spleen. This article deals with diseases of the splenic vasculature (aneurysms, arteriovenous fistula, splenic vein thrombosis, collateral circulation in portal hypertension) as well as vascular disorders affecting the splenic parenchyma (splenic infarct, Gamna-Gandy bodies). Primary vascular tumors and tumor-like conditions of the spleen will be discussed very briefly.

Identification of immunologic and pathologic parameters of death versus survival in respiratory tularemia

Francisella tularensis can cause severe disseminated disease after respiratory infection. The identification of factors involved in mortality or recovery following induction of tularemia in the mouse will improve our understanding of the natural history of this disease and facilitate future evaluation of vaccine candidate preparations. BALB/c mice were infected intranasally with the live vaccine strain (LVS) of F. tularensis subsp. holarctica and euthanized at different stages of disease to analyze the induction of immune molecules, gross anatomical features of organs, bacterial burdens, and progression of the histopathological changes in lung and spleen. Tissue-specific interleukin-6 (IL-6), macrophage inflammatory protein 2, and monocyte chemotactic protein 1 were immune markers of mortality, while anti-LVS immunoglobulin M and IL-1beta were associated with survival. Moribund mice had enlarged spleens and lungs, while surviving mice had even more prominent splenomegaly and normal-appearing lungs. Histopathology of the spleens of severely ill mice was characterized by disrupted lymphoid follicles and fragmented nuclei, while the spleens of survivors appeared healthy but with increased numbers of megakaryocytes and erythrocytes. Histopathology of the lungs of severely ill mice indicated severe pneumonia. Lungs of survivors at early time points showed increased inflammation, while at late times they appeared healthy with peribronchial lymphoid aggregates. Our results suggest that host immune factors are able to affect bacterial dissemination after respiratory tularemia, provide new insights regarding the pathological characteristics of pulmonary tularemia leading to systemic disease, and potentially identify immune markers associated with recovery from the disease.

[Chronic fever associated with splenic abscess due to Staphylococcus epidermidis]

Occult abscesses are frequent causes of chronic fever. Splenic abscesses are rare entities that are usually associated with underlying conditions such as abdominal surgery, endocarditis or immunodepression. We report on the case of a patient with prolonged fever caused by a splenic abscess, whose main differential diagnosis was visceral leishmaniasis. However, this condition was probably related to abdominal trauma. The treatment consisted of antibiotics followed by splenectomy.

Infarcted splenule--a case report

A 38-year-old woman presented with abdominal pain and left shoulder pain. A computed tomography scan was obtained, which demonstrated a rounded soft tissue density with surrounding stranding. It was interpreted as an infarcted splenule. Due to the increasing severity of the patient's symptoms, a laparoscopic exploration was performed. Pathology demonstrated an infarcted splenule. As infarcted splenules are rare, an understanding of its pathogenesis and familiarity with the corresponding imaging findings may be helpful for its diagnosis in the patient with the appropriate clinical scenario. It is important to recognize this entity as a cause of abdominal pain that can be managed nonsurgically.

Solitary splenic lesions

Solitary splenic lesions are unusual. A differential diagnosis can be organized around their basic imaging appearance as either predominantly cystic or solid. Other imaging characteristics, including vascular enhancement and activity on Tc-99m sulfur colloid scan, as well as clinical history may narrow the diagnostic possibilities. Cystic lesions include post-traumatic, inflammatory and infectious pseudocysts, congenital cysts, lymphangiomas and cystic metastasis. Solid lesions include both nonneoplastic lesions such as splenic hamartoma, benign tumors such as hemangioma and malignant masses including lymphoma and angiosarcoma. Percutaneous biopsy may be used for histologic diagnosis when required.

Congenital anomalies of the spleen

Various congenital anomalies may affect the spleen, starting with common anomalies, such as an accessory spleen, up to rare conditions such as a wandering spleen and polysplenia. Most of these anatomic variants have no clinical significance; they need, however, to be recognized by the radiologist as such. Awareness of these variants is important for the radiologist to interpret the findings correctly and avoid mistaking them for a clinically significant abnormality. In this review we illustrate the spectrum of congenital anomalies of the spleen and stress pitfalls and possible complications resulting from these anomalies.

Multiple lesions of the spleen: differential diagnosis of cystic and solid lesions

Lesions in the spleen may be encountered in a variety of clinical settings ranging from asymptomatic patients to patients who are critically ill. Etiologies for multifocal splenic lesions include infectious and inflammatory processes, primary vascular and lymphoid neoplasms, metastatic disease, vascular processes, and systemic diseases. There is often overlap in the imaging appearance alone, so the clinical setting is very helpful in differential diagnosis. In the immunocompromised patient, multiple small splenic lesions usually represent disseminated fungal disease and microabscesses. The spleen is a relatively rare site for metastatic disease; patients with metastatic lesions in the spleen usually have disease in other sites as well. Breast, lung, ovary, melanoma, and colon cancer are common primary tumors that metastasize to the spleen. Vascular neoplasms of the spleen represent the majority of the nonhematologic/nonlymphoid neoplasms and commonly produce multifocal lesions. Splenic infarcts may be seen with localized processes such as portal hypertension or pancreatitis, or may arise from an embolic source. Radiologists should be aware of the spectrum of processes that may involve the spleen and the clinical context in which they occur.

MRI features of intrahepatic extramedullary haematopoiesis in sickle cell anaemia

Extramedullary haematopoiesis (EMH) is a reactive mechanism by which blood cells are produced outside of the bone marrow to supplement insufficient production or increased destruction of erythrocytes. EMH is uncommon in sickle cell anaemia (SCA). We report the first case of focal intra-hepatic EMH in SCA depicted on MRI occurring in a 32-year-old woman with homozygote SCA and in view of previously published data, highlight the diagnostic features suggesting a differential diagnosis with other focal liver lesions including infectious, inflammatory or primary liver tumors.