Spleen peliosis

Spleen peliosis also called peliosis of the spleen, splenic peliosis or peliosis lienalis is an extremely rare benign blood vessel condition characterized by multiple, randomly distributed, blood-filled and cyst-like cavities throughout the spleen ¹⁾, ²⁾. The size of the lesions may vary from 1 millimetrer to several centimeters ³⁾. Peliosis is a term derived from the Greek pelios, which means “dusky” or “purple,” referring to the color of the liver tissue with peliosis ⁴⁾, ⁵⁾. Spleen peliosis has also been reported, either alone ⁶⁾, ⁷⁾, ⁸⁾, ⁹⁾ or with peliosis hepatis (hepatic peliosis or liver peliosis) ¹⁰⁾, ¹¹⁾, ¹²⁾, ¹³⁾, ¹⁴⁾, ¹⁵⁾, ¹⁶⁾. Spleen peliosis often presents with spontaneous rupture of the spleen and requires urgent surgical intervention ¹⁷⁾), ¹⁸⁾, ¹⁹⁾, ²⁰⁾, ²¹⁾, ²²⁾, ²³⁾, ²⁴⁾, ²⁵⁾, ²⁶⁾, ²⁷⁾, ²⁸⁾, ²⁹⁾, ³⁰⁾, ³¹⁾. Numerous associations with medications and other conditions have been described in the literature, emphasizing the limited understanding of spleen peliosis ³²⁾. However, spleen peliosis may also be recognized as an incidental finding on computed tomography (CT) scans or at autopsy ³³⁾, ³⁴⁾, ³⁵⁾, ³⁶⁾, ³⁷⁾, ³⁸⁾, ³⁹⁾, ⁴⁰⁾.

Spleen peliosis may be idiopathic or associated with infections such as tuberculosis and Bartonella, hematological diseases such as myeloma, myelofibrosis, and Hodgkin’s disease and with the use of androgenic steroids and erythropoetin. Patients with isolated splenic peliosis may be asymptomatic or describe abdominal discomfort. It is often detected as an incidental finding on abdominal imaging or when spontaneous rupture occurs.

Spleen peliosis discovered on imaging should immediately prompt further evaluation. A differential diagnosis will often include malignant, infiltrative, or infectious conditions, as well as post-traumatic splenic cysts. The cysts of spleen peliosis are blood-filled and innumerable in quantity, distinguishing them from post-traumatic fluid-filled cysts of the spleen. Isolated peliosis of the spleen is extremely rare, and is therefore infrequently considered ⁴¹⁾, ⁴²⁾, ⁴³⁾, ⁴⁴⁾. Imaging modalities for further assessing the spleen vary given the reason for testing and the differential diagnosis; they often include ultrasound, CT, positron emission tomography with CT (PET-CT), and magnetic resonance imaging ⁴⁵⁾, ⁴⁶⁾, ⁴⁷⁾. Despite these various imaging modalities, imaging may be inadequate for establishing a clear diagnosis ⁴⁸⁾, ⁴⁹⁾. While spleen peliosis often exists without symptoms, atraumatic spleen rupture, requiring urgent surgical intervention is a well-established presentation of spleen peliosis ⁵⁰⁾), ⁵¹⁾, ⁵²⁾, ⁵³⁾, ⁵⁴⁾, ⁵⁵⁾, ⁵⁶⁾, ⁵⁷⁾, ⁵⁸⁾, ⁵⁹⁾, ⁶⁰⁾, ⁶¹⁾.

As there are no clear published guidelines on the management of spleen peliosis, the definitive management of splenic rupture due to peliosis is emergency splenectomy ⁶²⁾, ⁶³⁾, ⁶⁴⁾, ⁶⁵⁾. However, prophylactic splenectomy is still debatable if accidental radiological findings were established upon regular check-ups or unrelated complaints ⁶⁶⁾.

Figure 1. Spleen peliosis

Footnotes: Contrast-enhanced CT scan from a 44-year-old otherwise healthy man presented with left-upper quadrant and left-shoulder pain. The patient denied trauma. A CT scan revealed splenomegaly with multiple splenic cysts and free intraperitoneal fluid consistent with blood. (A) Coronal view, (B) Axial view at the level of L1, (C) Axial view at the level of T12. Significant splenomegaly (14 × 11 × 9 cm). Multiple, loculated, cystic lesions are noted throughout the spleen. The largest cystic lesion measures 9.3 cm in diameter. A minor hemoperitoneum (not visible) was present on the scan.

[Source ⁶⁷⁾ ]

Figure 2. Spleen peliosis ultrasound

Footnote: A 3-year-old girl with splenic peliosis. Longitudinal ultrasonography of the spleen shows splenomegaly and multiple poorly defined hypoechoic nodules (arrow).

[Source ⁶⁸⁾ ]

Figure 3. Spleen peliosis rupture

Footnotes: (A) Spleen ultrasound appearance at diagnosis. (B) Ultrasound spleen appearance in peliosis rupture. Ultrasonographic imaging showed inhomogeneous splenic parenchyma and increased size. (C) Abdominal computer tomography (CT) frame. CT showed hemoperitoneum and marked splenomegaly (with a pole-to-pole diameter of about 200 mm) with many hyperdense areas.

[Source ⁶⁹⁾ ]

Spleen peliosis cause

The cause of spleen peliosis remains unclear ⁷⁰⁾. Several causative factors were suggested to be associated with peliosis in the spleen, including the following: intravenous drug abuse, the usage of anabolic steroids, danazol, chronic alcohol use, granulocyte colony-stimulating factor (GSCF) use, tamoxifen, azathioprine, androgens, chemotherapy, liver cirrhosis, tuberculosis, oral contraceptive pills, human immunodeficiency virus (HIV), Hodgkin’s disease, aplastic anemia, and myeloma ⁷¹⁾, ⁷²⁾, ⁷³⁾, ⁷⁴⁾, ⁷⁵⁾, ⁷⁶⁾, ⁷⁷⁾, ⁷⁸⁾, ⁷⁹⁾, ⁸⁰⁾, ⁸¹⁾, ⁸²⁾, ⁸³⁾, ⁸⁴⁾, ⁸⁵⁾, ⁸⁶⁾, ⁸⁷⁾, ⁸⁸⁾, ⁸⁹⁾, ⁹⁰⁾, ⁹¹⁾, ⁹²⁾, ⁹³⁾, ⁹⁴⁾. A number of reported patients were also noted to have blood disorders including multiple myeloma, aplastic anemia, Hodgkin disease, and myelofibrosis ⁹⁵⁾, ⁹⁶⁾, ⁹⁷⁾, ⁹⁸⁾, ⁹⁹⁾, ¹⁰⁰⁾, ¹⁰¹⁾, ¹⁰²⁾, ¹⁰³⁾, ¹⁰⁴⁾.

Preliminary evidence links the development of peliosis to angiogenesis (formation of new blood vessels) due to elevated levels of vascular endothelial growth factor (VEGF) ¹⁰⁵⁾. VEGF is a fundamental regulator of physiologic angiogenesis. Elevated VEGF levels are known to be associated with tumor progression and poor outcomes in a number of cancers. A condition resembling peliosis has been demonstrated in mice with elevated VEGF levels, that were found to have massively dilated hepatic sinusoids and endothelial cell proliferation and apoptosis ¹⁰⁶⁾. The experimental link to elevated VEGF levels, warrants investigation into the treatment of peliosis with anti-angiogenic factors ¹⁰⁷⁾.

Spleen peliosis risk factors include:

• use of anabolic steroids
• hematological conditions such as aplastic anemia
• wasting diseases such as
• tuberculosis
• AIDS
• concurrent malignancy

Spleen peliosis symptoms

Patients with spleen peliosis are commonly asymptomatic, and splenic peliosis may present as an incidental finding during imaging studies for other diseases, at autopsy, or with spontaneous rupture of the spleen after minimal or no trauma ¹⁰⁸⁾. Although uncommon, some reports suggest that males, ages > 20 years, presence of splenomegaly, and use of chemotherapy might be associated with increased risk of spontaneous splenic rupture in hematology ¹⁰⁹⁾. One literature review has shown that all the reported spleen peliosis cases collected from 1980 till 2016 had either presented with abdominal pain or circulatory shock ¹¹⁰⁾. Most cases of spleen peliosis are associated with peliosis hepatis (peliosis of the liver) ¹¹¹⁾.

Spleen peliosis diagnosis

Spleen peliosis hepatis is very difficult to diagnose because it is usually asymptomatic, and extreme rarity. Peliosis diagnosis is usually obtained after histopathological examination of the resected organ or at autopsy. Radiological imaging shows a broad spectrum of appearances because of its dependence on the blood supply to the lesions. Ultrasound shows multiple poorly defined hypoechoic lesions (Figure 2) and hyperechoic thrombosis ¹¹²⁾. The finding of cyst-like hypodense lesions which do not cause mass effect on vessels on contrast-enhanced CT should alert the radiologist to the diagnosis of spleen peliosis. This is of importance in recognizing the risk of spontaneous splenic rupture and in avoiding interventional procedures, such as liver biopsy or percutaneous transhepatic cholangiography, which may precipitate life-threatening iatrogenic organ rupture.

Peliosis histological appearance is characterized by multiple blood-filled cystic cavities primarily involving the mononuclear phagocytic system (liver, spleen, bone marrow, and lymph nodes).

Once the presence of peliosis has been established it is proposed that all necessary investigations be pursued to detect its presence in other organs and to establish a possible cause ¹¹³⁾. The implications for this are clear. Spontaneous rupture of the spleen remains an ever-present threat. Physicians should be mindful of this in the event that anticoagulation or thrombolysis is being considered. In addition, the presence of peliosis may prompt the investigation and subsequent discovery of equally serious underlying conditions, for example immunodeficiency or malignancy.

Spleen peliosis treatment

Hemorrhage associated with splenic peliosis is quite amenable to surgical therapy if recognised and treated promptly ¹¹⁴⁾. The existing literature does not however explore the surgical management of patients in whom an incidental diagnosis of splenic peliosis has been made. The introduction of laparoscopic splenectomy has reduced significant morbidity when compared with open surgery ¹¹⁵⁾. Prophylactic laparoscopic splenectomy has been advocated to prevent organ rupture in conditions such as splenic sarcoidosis ¹¹⁶⁾. The role of elective splenectomy in splenic peliosis is not known.

From the patient’s perspective, lifestyle changes may be necessary. Younger patients should be encouraged to avoid high-risk activities, for example, contact sports ¹¹⁷⁾. It would seem wise to avoid or discontinue the oral contraceptive pill, and seek alternative forms of contraception. In addition any attending physician should be aware when other medications thought to cause peliosis are being considered ¹¹⁸⁾.