A previously healthy 15-year-old boy was admitted to our hospital for investigation of a large abdominal mass that had appeared 3 months earlier. He also complained of difficulty in eating large amounts of any food or fluid because of an immediate sensation of fullness. He complained of no other symptoms, and there was no fever, weight loss or sweating. His family history of disease was negative.
On physical examination, the boy was tall and thin (weight, 50.1 kg; height, 172 cm, body mass index, 16.9; 3%-10% ile for age), and a prominent abdominal tumefaction was easily visible in the upper left abdomen. The mass was tender, but painless, apparently well-defined and mobile at the surface. It seemed to be within the spleen, with its lower limit palpable at the level of the umbilicus line. There was no hepatomegaly or enlarged lymph nodes.
Laboratory findings showed moderate thrombocytopenia and leukopenia (platelet count, 104,000; white blood cell count, 3310; neutrophils, 46%; lymphocytes, 42%; blast forms, 0%), hemoglobin within normal range (hemoglobin, 13.5 g/dl; mean corpuscular volume, 87fL) and normal values of lactic dehydrogenase (242 U/L), erythrocyte sedimentation rate, C-reactive protein, immunoglobulin, hepatic and renal function, cholesterol and triglycerides. Partial thromboplastin time was 1.31% of our laboratory standard. Prothrombin time was 68% of standard. International normalized ratio was 1.11. Fibrinogen concentration was 230 mg/dl.
Abdominal ultrasound and computed tomography scan (Fig. 1) revealed a large mass (approximately 17 cm) within the spleen, with well-defined margins and semi-liquid content. The mass did not present any enhancement on computed tomography scan. There were no abnormal findings in the liver; there were not enlarged abdominal lymph nodes. Chest radiograph was negative.
What is the likely diagnosis?
b) Pyogenic abscess of the spleen
c) Echinococcus cyst
d) Traumatic hematoma
e) Splenic cyst
Our hypothesis, based on its radiologic appearance, was that of a non-parasitic splenic cyst, and splenectomy was duly performed. Histopathologic findings revealed that the cyst was a mesothelial splenic cyst (the fibrocollagenous cyst wall was lined by cuboidal to low columnar non-ciliated epithelium, or mesothelial-like epithelium). The patient recovered uneventfully. The thrombocytopenia and leukopenia had resolved by follow-up. The coagulation disorder was explained by a concomitant factor VII deficiency.
The possibility of lymphoma was entertained because of concomitant finding of thrombocytopenia and leukopenia. Nevertheless, this hypothesis was excluded on the basis of bone marrow analysis with lymphocyte immunotypization. Also, the radiologic appearance was untypical because of absence of enhancement on computed tomographic scan. The hypothesis of pyogenic abscess was ruled out because of absence of fever and normal erythrocyte sedimentation rate and C-reactive proteinvalues. The hypothesis of echinococcosis was unlikely given the absence of liver lesions. The hypothesis of hematoma was improbable because the boy had no history of abdominal trauma.
Non-parasitic splenic cysts are unusual and are usually reported anecdotally (1). Their pathogenesis is only conjectural, and numerous hypotheses have been put forward. The most likely one is a congenital origin, with a lining derived from mesothelium (1). Trauma does not play a primary role in pathogenesis. The cystic nature of the lesion can be established by various radiologic studies such as ultrasonography, computed tomography and magnetic resonance imaging (2). These cysts are usually unilocular with characteristic gross features and sometimes calcified. The final diagnosis, however, is made at histology. Despite being asymptomatic, except for the mass and the pain in the abdomen, they can become infected or ruptured which means an acute abdominal emergency (2). Cysts that are symptomatic or larger than 5 cm in diameter should be removed by partial splenectomy or near-total cystectomy or "decapsulation" by the open or laparoscopic approach (1,3). In the present case, the large size of the cyst made partial splenectomy impossible.
1. Morgenstern L. Non parasitic splenic cysts: pathogenesis, classification, and treatment. J Am Coll Surg.
2. Reddi VR, Reddy MK, Srinivas B. Mesothelial splenic cyst: a case report. Ann Acad Med Singapore.
3. Calisti A, Perrotta ML, Molle P. Epithelial splenic cyst in children: surgical treatment by cyst-wall "peeling". Pediatr Surg Int