A splenic ‘cyst’: histology confirmed splenic sarcoma

Abstract

Primary malignant fibrous histiocytoma, now classified as pleomorphic undifferentiated sarcoma, is the most common soft-tissue sarcoma in adult life. Primary splenic pleomorphic undifferentiated sarcoma is extremely rare and aggressive, and is associated with a poor prognosis; only 14 cases of splenic pleomorphic undifferentiated sarcoma have been documented in the English literature. We discuss a case of a 56-year-old woman with iron-deficiency anaemia, early satiety and left upper-quadrant pain, who was preoperatively diagnosed with a large splenic cyst following thorough investigation. This was excised in an elective procedure. Unfortunately, histology confirmed splenic pleomorphic undifferentiated sarcoma. Following a review and summary of the literature, we discuss key differentials between splenic cysts and splenic pleomorphic undifferentiated sarcoma. This case highlights that iron-deficiency anaemia is unusual in splenic cysts and more sinister causes must be considered.

Background

Primary sarcomas of the spleen are uncommon, with only approximately 90 reported in international literature.¹ Primary malignant fibrous histiocytoma, now classified as pleomorphic undifferentiated sarcoma, is the most common soft-tissue sarcoma in adult life, particularly affecting the extremities, with two-thirds affecting the lower limbs.² Primary splenic pleomorphic undifferentiated sarcoma is extremely rare and aggressive, and is associated with a poor prognosis. A relatively recent literature review found only 14 cases of pleomorphic undifferentiated sarcoma of the spleen; our own literature review could not find any further published cases in the English literature on Medline.³ We discuss a case of pleomorphic undifferentiated sarcoma diagnosed preoperatively as a splenic cyst.

Case history

A 56-year-old fit and well postmenopausal woman presented to the upper gastrointestinal surgical team with iron-deficiency anaemia (haemoglobin 108g/l, white cell count 11.6 × 10⁹, platelets 578 × 10⁹, mean corpuscular volume 77.4fl) and early satiety. It was also noted that, for three months, she had experienced intermittent left upper-quadrant pain radiating to her left shoulder and the left side of her neck; one episode of such pain resulted in attendance to the emergency department. An electrocardiogram and chest radiograph were normal. An abdominal ultrasound arranged in the community prior to the clinic appointment identified a likely 11.5cm, well-circumscribed avascular cystic lesion, possibly a pancreatic or splenic cyst. There were no other gastrointestinal, respiratory or cardiac symptoms. Her only medication included hormone replacement therapy and naproxen. She smoked and consumed alcohol socially. There was no significant family history. Clinical examination demonstrated mild left upper-quadrant tenderness with no palpable mass.

An oesophagogastroduodenoscopy was duly organised and indicated external compression of the fundus of the stomach but was otherwise unremarkable, as was colonoscopy. An abdominal computed tomography (CT) with contrast identified a unilocular splenic cyst with a maximum diameter of 15cm, with coarse mural calcification and a focus of soft tissue density at 12 o’clock (Fig 1). The splenic lesion exerted mass effects with an elevated left hemidiaphragm and pleural reaction at the lung base.

Figure 1.

Preoperative abdominal computed tomography with contrast, indicating the splenic ‘cyst’.

An elective open splenectomy via a rooftop incision was performed following recommendation from the local multidisciplinary team. Intraoperatively, dense adhesions between the lesion and left lobe of liver as well as left hemidiaphragm were evident. The spleen was excised completely with the lesion intact, together with a small (2.5 × 3.0cm) segment of affected diaphragm. The patient had an uneventful postoperative recovery.

Unexpectedly, the specimen histology confirmed a splenic sarcoma. Histology indicated a grade 3 sarcomatous lesion involving the spleen. Macroscopically, the cyst contained necrotic yellow/yellow-grey material with a 1cm hyalinised wall, focal calcification and tumour nodules up to 2.5cm. Microscopically, there were irregular spindle cells, brisk mitotic activity, irregular cytoplasmic borders and variable nuclear polymorphism with some areas of tumour giant cells. The lesion was positive for CD31, but negative for CD34, S-100, HMB-45, Melan-A, DOG1, CKIT and pancytokeratin.

A follow-up CT at two months indicated a 42mm soft-tissue mass bridging the left hemidiaphragm, suggesting potential residual disease. Despite further aggressive surgical resection of the left hemidiaphragm and lower lobe of the left lung, margins again were not clear. Subsequent imaging within a few months after this surgery has now indicated metastatic disease to upper abdominal lymph nodes.

Discussion

In comparison with pleomorphic undifferentiated sarcoma, splenic cysts are relatively more common, particularly in younger women, and are often present as a painless mass in the left upper quadrant.⁴ Initial investigation would be with ultrasound, as was the case here, and for unusually large lesions and to identify the site of origin, CT is also required. The CT findings in this case were all in keeping with a primary cyst.⁵ Although a hydatid cyst was considered, it was not consistent with the clinical history. Symptomatic or large (greater than 4cm) splenic cysts should be managed surgically after a multidisciplinary team approach. There is limited information regarding adjuvant therapy in cases of splenic pleomorphic undifferentiated sarcoma, partly because there is limited information on survival. All splenic pleomorphic undifferentiated sarcoma so far have been managed with splenectomy, more recently laparoscopically with similar outcomes.

Constitutional symptoms such as nausea, vomiting, fatigue and weight loss with or without local pressure effects due to splenomegaly are common in previously documented case reports, as is a mild iron-deficiency anaemia. However, iron-deficiency anaemia is unusual in simple splenic cysts and, as with other malignancies, should be cause for concern for a more sinister diagnosis than a splenic cyst.