Figure 1. PA (A) and lateral (B) CXR from a woman with wheezing demonstrating a right perihilar nodule projecting within the lingula (circled) with associated atelectasis. To view Figure 1 in a separate, enlarged window click here.
Figure 2. Inspiratory (A) and expiratory (B) axial CT images demonstrating a mass obstructing the lingular bronchus (*) with post-obstructive mucus plugging (arrow) and air-trapping (circled). Axial image from an FDG PET-CT (C) demonstrates moderate FDG uptake within the nodule (arrowhead). No other areas of tracer uptake were seen to suggest nodal metastatic disease. To view Figure 2 in a separate, enlarged window click here.
Figure 3. Images from virtual bronchoscopic reconstructions from the patient’s CT (A) demonstrating a nodule obstructing the lingular bronchus. Image from bronchoscopy (B) obtained just prior to biopsy correlates nicely with virtual bronchoscopic findings. To view Figure 3 in a separate, enlarged window click here.
Figure 4. Low-power (A) and high-power (B,C) hematoxylin & eosin-stained pathology slides from the nodule demonstrating submucosal tumor adjacent to airway cartilage (*). The tumor contains some squamoid-appearing cells (B) as well as some mucinous cells (C, arrows) and intermediate-appearing cells (C, arrowhead). To view Figure 4 in a separate, enlarged window click here.
A 61-year-old woman was for wheezing. She reported that the symptoms were sudden in onset and persisted for 2 months without improvement. There was no infectious prodrome, no history of an aspiration event, and the symptoms had no exacerbating or relieving factors. The patient reported a past medical history of reflux (controlled on omeprazole), dyslipidemia, hypertension, and migraine headaches. Her past surgical history includes remote histories of breast augmentation, hysterectomy and salpingo-oophorectomy, cholecystectomy, and urethral sling. The patient was a never-smoker with no history of illicit drug use, travel, or exposures. Family history was non-contributory. The patient medications included Crestor, Thiazide, Imitrex, Losartan, and Omeprazole. No known drug allergies.
Her vital signs were normal. Physical exam demonstrated an inspiratory wheeze which was diffuse and best appreciated anteriorly. A PA and Lateral chest x-ray was done at the time of initial referral (Figure 1). A CT scan was subsequently obtained (Figure 2), the results of which led to a PET-CT (Figure 2) and, eventually, bronchoscopy with biopsy (Figure 3). Pathological results were consistent with a low-grade mucoepidermoid carcinoma (MEC) (Figure 4). The patient subsequently underwent left upper lobectomy with lymph node dissection. Surgical pathology demonstrated a 2.5 cm well-differentiated MEC with negative margins; all sampled lymph nodes were negative for malignancy.
MEC in the lungs is rare, accounting for 0.1%-0.2% of pulmonary malignancies (1). These tumors are thought to arise from minor salivary glands in the tracheobronchial tree (2). They are classified as low grade or high grade based on histological criteria (3). On imaging, these tumors are more common in lobar or segmental airways and tend to be round or lobular with well-circumscribed margins. They tend to be vascular and demonstrate heterogeneous enhancement on contrast-enhanced CT. Because they arise from the lining of the airways, they are often associated with post-obstructive findings like mucus plugging, air-trapping, atelectasis, and pneumonia. Patients usually present with symptoms related to endoluminal growth, including persistent cough/sputum, wheezing, dyspnea, hemoptysis, and/or recurrent pneumonias. Patients are often initially mis-diagnosed with asthma, bronchitis, or COPD. The patients frequently do not have a smoking history, which can be helpful when ordering a differential diagnosis. The lesions often demonstrate submucosal growth so bronchial washings/brushings are often negative, as was the case for this patient. This case is a good reminder of the “other” endobronchial tumors, which also include carcinoid tumors (well-circumscribed, vascular, more common in bronchi as opposed to trachea), adenoid cystic carcinoma (usually involve the trachea as a “cylindroma”, have submucosal and perineural growth), sarcomas (chondrosarcoma, sarcoma metastases), hamartomas (often contain fat and/or popcorn calcifications), and tracheobronchial papillomatosis (younger patients, multiple cavitary lesions) (4).
Clinton E. Jokerst MD, Matthew T. Stib MD, Carlos Rojas MD, Michael B. Gotway MD
Department of Radiology
Mayo Clinic Arizona
Phoenix, AZ USA
References
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- Ishizumi T, Tateishi U, Watanabe S, Maeda T, Arai Y. F-18 FDG PET/CT imaging of low-grade mucoepidermoid carcinoma of the bronchus. Ann Nucl Med. 2007 Jul;21(5):299-302. [CrossRef][PubMed]
- Yousem SA, Hochholzer L. Mucoepidermoid tumors of the lung. Cancer. 1987 Sep 15;60(6):1346-52. [CrossRef] [PubMed]
- Park CM, Goo JM, Lee HJ, Kim MA, Lee CH, Kang MJ. Tumors in the tracheobronchial tree: CT and FDG PET features. Radiographics. 2009 Jan-Feb;29(1):55-71. [CrossRef] [PubMed]