High riding pericardial recess was first reported by Choi et al1 in 2000.
It is not rare, being present in 2% to 6% of normal healthy individuals.2 It is a cranial extension of the pericardium which can be seen on a computerized tomography (CT) scan adjacent to the lower right paratracheal region in front of the brachiocephalic vessels.1–4 It is an upward extension of the superior pericardial recess, which can be seen just cephalad to the right pulmonary artery often as a “half moon” shape adjacent to the posterior wall of the ascending aorta.5 The high-riding pericardial recess is contiguous with this arising cranially from it. It is not associated with a pericardial effusion. It can be rounded, oval, or triangular and up to 4 cm long. It is usually molded by adjacent vessels and being fluid containing has a CT density of 10 to 20 Hounsfield units (HU). There is no mass effect on adjacent structures, which is sometimes seen with lymph nodes, and there is no peripheral contrast enhancement.
Endobronchial ultrasound transbronchial needle aspiration (EBUS TBNA) is increasingly being used to sample nodes in the right paratracheal position for diagnostic purposes.6,7 We present 2 cases of EBUS TBNA where the aspirated fluid and radiologic appearances were consistent with a high riding pericardial recess. In the first case, the entity was not suspected, partly because of adjacent pulmonary pathology, whereas in the second case high riding pericardial recess was suspected from CT appearance before performing EBUS TBNA.
MATERIALS AND METHODS
A 71-year-old woman was referred for further evaluation of a right paratracheal mass (26 mm×21 mm) and adjacent right upper lobe (RUL) pulmonary lesion (26 mm×17 mm). The CT was performed for staging of a low-grade follicular lymphoma proven by biopsy of enlarged axillary lymph nodes. There was a past smoking history of 10 pack years, so the differential diagnoses included primary lung cancer and pulmonary lymphoma. Conventional bronchoscopy and CT-guided fine needle aspiration (FNA) had been negative. CT density on the paratracheal and pulmonary lesions were 4 to 10 HU and 20 to 25 HU, respectively. Positron emission tomography (PET) scan showed mild uptake in the RUL lesion but no uptake in the right paratracheal region (Fig. 1).
At EBUS, there was no endobronchial lesion and applying the EBUS using Olympus Convex probe scope (BF-UC-260F-OL8), the right paratracheal region showed a dark area consistent with a fluid filled structure immediately next to the tracheal wall (Fig. 2). Aspirate of this region showed 15 mL of straw-colored fluid. On site, pathology showed only epithelial cells, some carbon pigment, and no lymphocytes or malignant cells. Formal cytology confirmed these findings.
Follow-up CT showed no change in the right paratracheal mass but the RUL pulmonary lesion enlarged slightly, and a repeat CT FNA of this lesion revealed adenocarcinoma. Lobectomy was performed; at this procedure the surgeon explored the right paratracheal region finding only an empty cystic structure lined by pericardium, which was confirmed on histology. The pathologic staging was therefore T1N0M0.
A 65-year-old woman presented with minor hemoptysis and fatigue. The patient was an ex-smoker with a 20 pack year history. Physical examination was unremarkable. A chest x-ray demonstrated a prominent right hilum. CT of the chest demonstrated a right paratracheal mass measuring 3.2 cm×2 cm. CT density of this lesion was −1.9 HU. No other focal pulmonary lesion was evident. A standard bronchoscopy had been normal and washings were negative for infection or malignancy.
At EBUS TBNA, a cystic lesion was identified using ultrasonography adjacent to the trachea at the right paratracheal position. Doppler ultrasound confirmed that the cyst was not vascular in nature in contrast to the strong vascular flow signal demonstrated in the adjacent azygous vein (Fig. 3 and Web Video: bronchoscopic view shows scope at lower right end of trachea, scope turned to 3-o'clock position. EBUS images first show the azygous vein as a circular lesion in top left of view, followed by the high riding pericardial cyst which occupies mid view. Color Doppler strongly positive in azygous vein and negative in cyst). Under ultrasound guidance, FNA of the lesion was performed. Fifteen milliliters of straw-colored fluid was aspirated from the lesion and sent for microscopy, culture, and cytologic analysis. The results of the fluid analysis revealed a marked lymphocytosis with mild atypia noted. No malignant cells were seen. The bacterial, mycobacterial, and fungal cultures were negative.
The patient subsequently underwent a PET scan, which demonstrated no fluorodeoxyglucose uptake in the region of interest, nor elsewhere. Serial chest CT scans will be performed.
It is important for practitioners of TBNA to be aware of this entity as it is not rare and a high riding paratracheal recess can mimic lymphadenopathy. Among the numerous CT radiologic features, density consistent with water is certainly useful and was demonstrated in both cases. The presence of fluid, absence of malignant cells, and the negative PET scans helped confirm the diagnosis. Surgical resection confirmed the diagnosis in the first case and to our knowledge this is the first report of a high riding pericardial cyst with surgical confirmation. The right lower paratracheal region is easily visualized with the convex probe bronchoscope and the normal vascular relations at the lateral aspect of the trachea (the azygous vein and superior vena cava) are well seen. However it could be possible to misinterpret the high riding pericardial recess as one of these vessels, and not be able to identify “the lesion.” This would be particularly true if color power Doppler was not used to confirm the absence of vascularity. We found the latter to be particularly useful as clearly it is incorrect to attempt needle aspiration on a lesion, which is thought to be vascular.
In both cases, only 1 aspirate of the cyst was required and these were performed without any adverse consequences.
This unusual cause for right paratracheal “lymphadenopathy”/soft tissue density is not the only pathological fluid-filled entity which can be recognized with EBUS. Bronchogenic cysts are the most common cystic lesions in the middle mediastinum and usually arise near the trachea. Although surgical resection is the therapy of choice because of frequent recurrence, there are 2 recent case reports of successful identification and aspiration with EBUS without recurrence over a follow-up period of 12 to 18 months.8,9 Lymphangiomas can have a similar CT appearance although they would be considerably more rare.10
In summary, at EBUS TBNA color power Doppler is very useful at the lower right paratracheal region to confirm a cystic lesion and should be used early in the procedure where the high riding pericardial recess is suspected on CT.
The authors thank Dr Karin Steinke, Radiologist, RBW Hospital for discussions and assistance with CT interpretation.
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