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Rare Diagnosis of a Multilobular Pulmonary Mass

      Case Presentation

      A 57-year-old woman was admitted to our hospital for an abnormal chest shadow found during routine chest radiography. She had no respiratory symptoms. Her medical history included dyslipidemia, and her surgical history included conization for cervical cancer at age 38 years. She was a social drinker and ex-smoker of approximately 10 cigarettes per day (from ages 20 to 30 years); she denied recreational drug use.
      A review of systems yielded negative results. The woman was afebrile with no acute distress. The respiratory and cardiac portions of the physical examination indicated no abnormalities. Her laboratory results also indicated no abnormalities. The patient’s chest radiograph revealed an oval nodule in the left lower lung field. Noncontrast CT imaging indicated a 3.4 × 2.4 cm, well-demarcated, lobular solid mass in the lower lobe of the left lung without lymphadenopathy. The tumor was slightly enhanced from 18 to 36 Hounsfield units on contrast-enhanced images (Fig 1).
      Figure thumbnail gr1
      Figure 1Axial and coronal sections of CT images of the lung demonstrating a well-demarcated, lobular, solid mass (black arrows) in the lower lobe of the left lung measuring 3.4 x 2.4 cm in diameter.
      We subsequently performed PET/CT scanning, which indicated slight accumulation in the mass and a maximal standardized uptake value of 1.59. There was no abnormal activity within the thoracic lymph nodes, and no extrathoracic abnormalities were present. The patient subsequently underwent endobronchial ultrasound-guided transbronchial biopsy of the left B9 (EBUS-GS-TBB) using a 2.0-mm radial EBUS probe (Olympus) (Fig 2). Cytology results suggested lymphoid cell infiltratation, and there were no signs of bacterial infection and epithelioid granulomas.
      Figure thumbnail gr2
      Figure 2Endobronchial ultrasound showing a low-echoic lobulated mass. Transbronchial biopsy of the left B9 was performed.
      Because of the location and mild uptake according to PET/CT imaging, nontuberculous mycobacteriosis, actinomycosis, and mucinous neoplasm were considered the differential diagnoses. We decided that surgical resection was necessary to confirm the diagnosis.
      The patient underwent video-assisted thoracoscopic left lower lobectomy with lymph node dissection. The postoperative course was uneventful, and she was discharged home on postoperative day 4.
      The macroscopic examination of formalin-fixed specimens revealed a solitary multilocular cystic lesion measuring 4.0 × 3.5 × 2.4 cm in the resected lung. According to the bacterial examination, the cyst contents comprised mucous fluid without bacteria. Each loculus was separated by a thin fibrous septum, and its inner surface appeared flat and smooth, thus indicating a cavernous appearance. No discernible nodules or evidence of hemorrhage were found (Fig 3). In addition, lung parenchyma other than the aforementioned lesion appeared essentially normal, without any emphysematous or cystic changes.
      Figure thumbnail gr3
      Figure 3Macroscopic finding of a 4.0 × 3.5 × 2.4 cm specimen. The cut surface shows a dilated multicystic lesion.
      Microscopic observation showed that the inner surfaces of these cysts were sparsely lined by bland cuboidal cells in the monolayer (Fig 4A). Immunohistochemical (IHC) staining showed that these cells were positive for CD31, CD34, and podoplanin (D2-40) and negative for cytokeratin (AE1/AE3) (Fig 4B). There were no histopathologic findings indicating pulmonary emphysema, interstitial pneumonitis, or lymphangioleiomyomatosis. There was also no evidence of malignancy, which might cause secondary multilocular expansion of the peripheral structures.
      Figure thumbnail gr4
      Figure 4A, Histologic analysis showing a cyst containing eosinophilic fluid. The cyst wall is lined with a single layer of endothelium. B, Immunohistochemical examination showed that the single layer of epithelial cells lining the cyst was positive for podoplanin and CD31.
      What is the diagnosis?
      Diagnosis: Pulmonary cavernous lymphangioma

      Discussion

       Clinical Discussion

      Lymphangiomas are rare, benign lymphatic malformations that are composed of cystically dilated lymphatic vessels, which are caused by a developmental defect or primary malformation of the lymphatic channels.
      • Hilliard R.I.
      • McKendry J.B.
      • Phillips M.J.
      Congenital abnormalities of the lymphatic system: a new clinical classification.
      They are classified into three pathologic categories: lymphangioma simplex, cavernous lymphangiomas, and cystic lymphangiomas. Lymphangiomas can occur in any part of the body; the most common sites are the neck (75%) and axilla (20%). Although mediastinal lymphangioma is not uncommon (0.7%-4.5%), especially in children, pulmonary lymphangioma is extremely rare. According to our literature search, only 17 cases, including the current case, have been reported in the international literature to date.
      • Minato H.
      • Kaji S.
      • Kinoshita E.
      • et al.
      Solitary intrapulmonary cystic lymphangioma in an infant: a case report with literature review.
      In terms of cavernous lymphangioma, only eight cases have been reported.
      • Drut R.
      • Mosca H.H.
      Intrapulmonary cystic lymphangioma.
      • Hamada K.
      • Ishii Y.
      • Nakaya M.
      • Sawabata N.
      • Fukuda K.
      • Suzuki H.
      Solitary lymphangioma of the lung.
      • Nakajima J.
      • Goto A.
      • Takamoto S.
      • Murakawa T.
      • Fukami T.
      • Kusakabe M.
      Invasive lymphangioma of the lung manifesting as a large pulmonary mass with hemoptysis: report of a case.
      • Shinohara S.
      • Nakanishi R.
      • Yasuda M.
      • Tanaka F.
      Rapid growing pulmonary cavernous lymphangioma after chronic process for ten years.
      • Takemura T.
      • Watanabe M.
      • Takagi K.
      • Tanaka S.
      • Aida S.
      Thoracoscopic resection of a solitary pulmonary lymphangioma: report of a case.
      • Wilson C.
      • Askin F.B.
      • Heitmiller R.F.
      Solitary pulmonary lymphangioma.
      An analysis of the complete series, including the current one, indicated that patient ages ranged from 2 days to 59 years. The female-to-male ratio was 7:10. One-half of the patients were asymptomatic, and the lesion was found accidentally on chest radiography or CT imaging; the rest caused a variety of symptoms such as cough, dyspnea, hemoptysis, retrosternal chest pain, pneumothorax, and respiratory distress.
      • Holden W.E.
      • Morris J.F.
      • Antonovic R.
      • Gill T.H.
      • Kessler S.
      Adult intrapulmonary and mediastinal lymphangioma causing haemoptysis.
      There is a tendency for adult patients to be asymptomatic and for pediatric patients to exhibit symptoms. This may be because the size of tumor compared with the size of the thoracic cavity is larger in children than in adults. The maximum diameter ranged from 1.5 to 18 cm. The lesions were randomly distributed without any propensity for the right or left lung.

       Radiologic Discussion

      The most common finding of lymphangioma on CT imaging is a uniformly cystic structure with smooth margins. Pulmonary lymphangiomas with a noncystic appearance (lobular solid mass, as in the present case) seem to be rare. Most of the previous cases involved a poorly demarcated mass with uniform density. In contrast, the current case involved a well-demarcated, lobular, solid mass.
      No definite enhancement was observed after IV administration of contrast material. MRI of lymphangiomas exhibits a signal similar to that of the muscle on T1-weighted images, with a marked signal increase on T2-weighted images that is greater than that of fat, thus reflecting the fluid content.
      • Shaffer K.
      • Rosado-de-Christenson M.L.
      • Patz Jr., E.F.
      • Young S.
      • Farver C.F.
      Thoracic lymphangioma in adults: CT and MR imaging features.
      Only two cases underwent PET-CT imaging, including the current case, and both cases showed slight accumulation.
      • Shinohara S.
      • Nakanishi R.
      • Yasuda M.
      • Tanaka F.
      Rapid growing pulmonary cavernous lymphangioma after chronic process for ten years.
      However, these findings are not sufficiently characteristic to reliably differentiate lymphangioma from non-small cell lung cancer, bronchogenic cyst, and hemangioma.
      There have been no reports of EBUS findings for pulmonary lymphangioma. In the current case, EBUS revealed a low-echoic cystic mass. It seemed more similar to the macroscopic image because CT imaging showed a solid mass. Therefore, EBUS imaging might be useful for diagnosing pulmonary lymphangiomas.

       Pathologic Discussion

      Several differential diagnoses should be addressed when localized multilocular cystic lesions of the peripheral lung are observed. Based on the macroscopic and histopathologic findings, in addition to the clinical information, pulmonary emphysema and lymphangioleiomyomatosis could be excluded. In cases of malignant neoplasms, primary lung or metastatic lesions might be the cause of cysts in the peripheral lung; however, this was not the case in the current patient. Regarding vascular lesions, there might be difficulty differentiating lymphangiomas from hemangiomas. The lack of evidence of hemorrhage in this case strongly suggested that this lesion was not hemangiomatous. For this differential diagnosis, the detection of IHC markers is useful.
      • Shinohara S.
      • Nakanishi R.
      • Yasuda M.
      • Tanaka F.
      Rapid growing pulmonary cavernous lymphangioma after chronic process for ten years.
      Among these, CD31, CD34, and podoplanin (detected by antibody D2-40) are widely used as markers of lymphangiomas, and a combination of these tests may increase the diagnostic accuracy.
      • Nakajima J.
      • Goto A.
      • Takamoto S.
      • Murakawa T.
      • Fukami T.
      • Kusakabe M.
      Invasive lymphangioma of the lung manifesting as a large pulmonary mass with hemoptysis: report of a case.
      CD31 and CD34 are relatively sensitive and specific markers of endothelial differentiation that are expressed in the majority of vascular tumors. Podoplanin is a cell surface sialoglycoprotein expressed in the lymphatic endothelium and select epithelia. In this case, by performing IHC staining using anti-CD31 and CD34 antibodies and D2-40, we clearly confirmed that this lesion consisted of cavernous lymphatic dilation. A combination of IHC stains would increase the diagnostic accuracy when differentiating lymphangioma from hemangioma.
      In terms of multilocular cyst formation, most lung lymphangiomas are characterized by a unicystic or paucicystic structure. A solitary lung lymphangioma with a cavernous appearance (as in the current case) seems to be rare.

      Conclusions

      We encountered a rare case of pulmonary cavernous lymphangioma. Lymphangioma should be considered as the differential diagnosis of a pulmonary tumor. We confirmed the diagnosis from surgical resected specimen. Postoperative imaging showed no recurrence for 1 year following surgery.

      Acknowledgments

      Financial/nonfinancial disclosures: None declared.
      Other contributions: CHEST worked with the authors to ensure that the Journal policies regarding patient consent to report information were met.

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