This paper highlights a very rare diaphragmatic origin of EES that initially presented with features of sub-acute intestinal obstruction. Clinicians should suspect EES as a differential in such varied presentations.

Keywords :

Ewing sarcoma; sarcoma; neoplasms; laparotomy

Introduction :

Ewing sarcoma (ES) is a malignant bone tumour that typically affects adolescents and has a rather aggressive course with 85-90% mortality due to metastasis despite treatment (1,2).

ES affects soft tissues and bones with a peaking incidence between the ages 15-20 years (1,3). The most common anatomical sites of ES include the pelvis, axial skeleton, femur and ribs (1,4). Extraskeletal Ewing’s sarcoma (EES) most commonly involves the upper thigh, hips, and shoulders, and has a reported incidence of 0.4 per million (5,6). EES presents as a rapidly growing mass and follows a bi-modal age distribution, peaking in ages <5 and >35 years (5,7). Very few cases of EES arising from the diaphragm have been reported, and primary diaphragmatic ES diagnosis is considered to be extremely rare (8,9). Here, we report a case of diaphragmatic EES in a 17-year-old male.

Case History/Examination :

We describe the case of a 17-year-old South Asian male presenting to the emergency department with complaints of abdominal pain and distension for the past 2 weeks and relative constipation for the past 2 days. He had a history of approximately 8 kg weight loss in the past 3-4 months and a chronic dry cough on and off. He had no history of fever, nausea, vomiting, loose stools, anorexia, dyspnea, palpitations, headache, seizures, vertigo, altered sensorium, burning micturition, jaundice, and rash. He had passed flatus 1 hour ago, but the stool was not passed.

On general physical examination, he had pallor, but no icterus, clubbing, cyanosis, lymphadenopathy, koilonychia or edema. On inspection, abdominal distension was noted with normal umbilicus. On palpation, the liver was enlarged with the lower border of the liver palpated 6 finger breadths below the right costal margin. On percussion, shifting dullness was elicited in the abdomen. The bowel sounds were exaggerated and the digital rectal examination was unremarkable. A working clinical diagnosis of “subacute intestinal obstruction” was made.

Differential Diagnosis, Investigation, and Treatment :

Ultrasound abdomen showed the liver span to be 14.5 cm, with dilation of gut loops, and a bulky echotexture of the pancreas. A large hypoechoic area with internal septations was found in the epigastrium (15x11x13 cm) with moderate-to-gross ascites with a fluid collection of ~1200 ml was also noted.

Contrast-enhanced computed tomography (CECT) scan of the thorax, abdomen and pelvis revealed a solid cystic area of 32 x 11 cm along the upper abdomen anteriorly with effacement of the anterior surface of the liver, stomach, and pancreas (Figure 1). Multiple loculations were seen on the superior aspect of this area with its lower limit reaching the iliac fossa inferiorly (Figure 2 and Figure 3). Mild-to-moderate right-sided pleural effusion causing basal atelectasis was also noted but no significant mediastinal lymphadenopathy was seen (Figure 4). CECT scan confirmed the presence of ascites. CECT scan was suggestive of a large hydatid disease and/or complicated abscess collection.

Differential diagnoses at this point were:

Due to the suspicion of hydatid disease, a hemagglutination test for Echinococcus was done which was negative (6.73 IU/ml). Due to the high prevalence of TB in South Asia, sputum samples were sent which were negative for the presence of tuberculosis.

Owing to the inconclusive serology and imaging, exploratory laparotomy was performed. Intraoperatively, an incident finding of a large irregular, highly vascular mass attached to segment VII of the liver and right hemidiaphragm, encroaching sub-diaphragmatic space was noted and was excised. Intraoperatively, anterolateral thoracotomy was also done to delineate the mass attached to the right hemidiaphragm. Along with this, approximately 1500 ml of malignant ascitic fluid was also drained. Metastatic lesions (seedlings) were observed on the lung surfaces and chest wall. The large tumour was also seen on the superior surface of the right hemi-diaphragm. Intraoperatively, the liver transplant unit was consulted to rule out the hepatic origin of the mass. The mass was concluded to be arising from the diaphragm or the right lateral abdominal wall.

Outcome and Follow-up :

Histopathology samples of the mass and cell cytology samples of the ascitic fluid were sent. A microscopic section of the mass revealed a malignant tumour made up of sheets and nests of round-to-oval cells with moderate-to-marked atypia, frequent mitosis, and a higher nuclear-to-cytoplasmic ratio, with extensive necrosis. Immunohistochemistry was positive for CD99 and NKX2.2 while it was negative for Desmin and Myo D1. A definitive diagnosis of “Ewing’s Sarcoma” was made.

Discussion :

ES is a malignant tumor that belongs to the ES family of tumours (ESFTs), which can be divided into skeletal-ES, EES, peripheral primitive neuroectodermal tumor (pNET) and Askin tumor of the chest wall (10). The most common sites of primary EES include intracranial, para-vertebral, thoracopulmonary, the extremities, kidneys, adrenals, pancreas, gastrointestinal, intraperitoneal, ovaries and urinary bladder (11). Some studies suggest a higher prevalence of EES in males, but controversies exist in the sex distribution of EES (7,11). Presenting symptoms of EES vary widely depending on the location of the primary tumor and the extent of local as well as distant invasion (11).

The absence of conclusive clinical symptoms often delays the management of EES. This case is particularly interesting since the patient presented with symptoms of subacute intestinal obstruction which later turned out to be diaphragmatic EES. Though small bowel EES has been described, it is also extremely rare (11). Raney et al studied 15 cases of diaphragmatic sarcomas and reported alveolar rhabdomyosarcoma to be the most common subtype of diaphragmatic sarcoma (8). EES was reported only in 3 of the studied 15 cases, emphasizing the rarity of the tumor (8). Studies indicate that patients with EES are more likely to have axial tumors (12).

On comparison of prognostic factors for ES and EES, no major differences have been reported (12). For EES, elevated baseline ESR has been demonstrated to have inferior event-free survival (12). EES patients with a primary tumor in the pelvis have shown improved survival characteristics (12). Imaging plays an important role in the diagnosis of EES. As EES is a malignant tumor, positron emission tomography/computed tomography (PET/CT) should be utilized as it has demonstrated appreciable sensitivity in detecting EES metastasis (13).

Surgery with complete excision of the tumor mass is the mainstay of treatment for localized EES. For more advanced EES, radiotherapy and chemotherapy are added to the treatment protocol to improve the progression-free survival period, prognostic outcomes, and clinical improvement. EES patients are more likely to receive surgery along with radiation than surgery alone, which can be explained by the fact that more EES patients have an axial location of the primary tumor that is not amenable to complete surgical resection with tumour-negative margins (12). The addition of chemotherapy to the management protocol has significantly improved survival rates of EES patients from 10% five-year survival for patients without chemotherapy to 70-80% five-year survival for patients who received chemotherapy (11).

Conclusion :

ES is a malignant and aggressive tumor which can also be found extraskeletally, called EES. The most common locations of EES are intracranial, para-vertebral, thoracopulmonary, and the extremities. The presenting features of EES depend on the location of the primary tumor, hence EES has a very varied presentation and is difficult to diagnose. Imaging should be used extensively to aid in the timely diagnosis of EES, as EES often presents at an advanced stage. For more advanced cases, PET/CT has proven to aid in the diagnosis of EES. The management protocol of EES includes extensive surgery with/without radiotherapy or chemotherapy, depending on the extent of invasion and metastasis. EES, albeit rare, should be kept as a differential diagnosis for ill-defined and atypical masses.

Author Contributions :

Ali Raza : Conceptualization; writing – original draft.Hritvik Jain : Methodology; writing – original draft; writing – review & editing. Ahmad Munib : Conceptualization; writing – original draft. Juhi Prashant Pujara : Writing – original draft. Mohammed Quader Naseer : Writing – original draft.Ankit Singh : Writing – original draft, writing – review & editing. Jyoti Jain : Writing – original draft.Prakriti Pokhrel : Writing – original draft.

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Figure Legends :

Figure 1: Axial section of CECT image showing a large solid cystic mass along the upper abdomen border anteriorly (white doughnut and white star representing the solid and cystic areas respectively). The lesion is also seen effacing the anterior surface of the liver (black arrow) and the stomach (white arrow).

Figure 2: Coronal section of CECT image showing multiple loculations at the superior aspect of the lesion (open block white arrow).

Figure 3: Coronal section of CECT image showing inferior extension of the lesion till right iliac fossa (doughnut and star representing solid and cystic areas of the lesion respectively).

Figure 4: Axial CECT image showing mild to moderate right-sided pleural effusion (open block white arrow).