Angioasarcoma of spleen

An angioasarcoma of the spleen is a rare malignent splenic neoplasm. The term is usually given to describe a primary angiosarcoma of the spleen although angiosarcoma elsewhere can also rarely metastasise to the spleen.  Despite its absolute rarity, a splenic angiosarcoma is considered the most common primary splenic malignancy ².

Epidemiology

The general consensus is that there is no recognised gender predilection (occurs almost equally in females and males)¹. Occasional publication however suggest a slight male predilection ⁴ .The peak incidence is thought be around the 6^th decade.

Clinical presentation

Clinical symptomatology can be highly variable, often posing difficult diagnostic problems.

Pathology

Macroscopic examination often shows splenomegaly with cut sections revealing discrete lesions in a majority of cases. These can range from well-circumscribed firm nodules to poorly delineated foci of necrosis and haemorrhage associated with cystic spaces. Microscopically, the tumours are often heterogenous. The lesions typically demonstrate focal vasoformative component lined by atypical endothelial cells. Solid sarcomatous, papillary, and epithelioid growth patterns can be observed.

Associations

Unlike with primary hepatic angiosarcoma, there is no known association between splenic angiosarcoma and occupational exposure to chemicals, such as vinyl chloride or arsenic, or prior injection with the contrast agent thorium dioxide ⁴.

Radiographic features

Ultrasound

Reported sonographic features are non specific and include splenomegaly with  cystic and solid masses with mixed echogenicity ⁴.

CT

CT may show solitary or multiple nodular masses of heterogeneous low attenuation in an enlarged spleen. There is generally irregular and poorly defined contours, is often detected in a globally enlarged spleen ¹⁶.

Occasional large subcapsular intrasplenic or perisplenic extracapsular blood collections (haemoperitoneum) may be present.

Some of these masses may show peripheral enhancement  with the margins of the lesions are often irregular or poorly marginated.

• pre-contrast CT - the tumours may appear hyperattenuating due to components of acute hemorrhage.
• dynamic contrast-enhanced CT scans - the lesions may exhibit substantial peripheral contrast enhancement similar to that of hepatic haemangiomas ⁴.

On occasion, CT scans may show a moderate splenomegaly with micronodular involvement of the organ ¹⁶.

MRI

Reported MRI features include

• T1 and T2 :
  • nodular hypointense (relative to the normal adjacent splenic parenchyma) masses on both T1- and T2- weighted images -
  • large masses with increased signal intensity on both T1- and T2-weighted images that are likely related to areas of subacute haemorrhage, as well as tumour necrosis
  • areas of decreased signal intensity within the tumour, owing to chronic haemorrhage with haemosiderin deposition.
• C+ (Gd) : usually shows intense and multinodular (heterogenous ¹⁵) enhancement with focal areas of non-enhancement - likely represeting intratumoral haemorrhage and necrosis

Complications

• spontaneous splenic rupture ^2,4 : can occur in upto 30% of cases ⁴

Treatment and prognosis

It is an extremely aggresive fatal neoplasm at is almost universally fatal (median survival at aprroximately 24- 36 months at time of inital writing¹¹) desptie treatment ^3,5. Distant metastases occur most frequently in the liver (approximately 70% of cases), lung, pleural lymph nodes, bone, and brain. Prompt splenectomy prior to splenic rupture may improve survival ⁵.

Etymology

It was first described in 1879 by T Langhans ¹

Differential diagnosis

General imaging differential considerations include vascular splenic lesions such as 

• splenic haemangioma
• Littoral cell angioma of spleen
• lymphangioma of spleen
• haemangiopericytoma of spleen

See also

• angiosarcoma - general
• splenic lesions and anomalies