Primary Pulmonary Epithelioid Hemangioendothelioma: A Rare Cause of PET-Negative Pulmonary Nodules

We report here a case of primary pulmonary epithelioid hemangioendothelioma diagnosed in a 67-year-old Caucasian man, presenting with exertion dyspnoea, dry cough, and multiple bilateral pulmonary nodules revealed by computed tomography. At the 18F-fluorodeoxyglucose positron emission tomography, these nodules were negative. The histopathological diagnosis was made on a pulmonary wedge resection (performed during video-thoracoscopic surgery).


Introduction
Pulmonary epithelioid hemangioendothelioma (PEH) is a rare, low-to intermediate-grade tumor of endothelial origin [1] with around 120 cases reported in the literature [2]. At the onset, the patients are usually asymptomatic or present with nonspecific symptoms (such as weight loss, fatigue, dyspnoea, cough, and chest pain). Chest imaging usually shows the presence of multiple, bilateral small pulmonary lesions. The diagnosis usually requires a lung biopsy. The treatment is still not standardized. Surgery is suggested in presence of a solitary nodule or few unilateral nodules. Instead if the lesions are unresectable or multiple and bilateral several chemotherapy protocols have been used. The prognosis is variable with a median survival of 4-5 years.

Case Report
A 67-year-old Caucasian man, lifelong nonsmoker, with no prior history of lung diseases, was referred to our university hospital for the presence, in the last 3 months, of exertion dyspnoea (grade 1 according to the Medical Research Council scale [3]) and dry cough. He had worked as an employee without occupational exposures of clinical relevance. His past medical history was characterized by an herniated lumbar disc, systemic arterial hypertension (treated with calcium blockers), diabetes mellitus (treated with oral hypoglycaemic agents), and polycythemia vera (diagnosed in 2007 and treated from 2008 with hydroxyurea). Physical examination was unremarkable. Arterial blood gases analysis performed with the patient breathing room air demonstrated normal values (pH 7.40, PaCO 2 43 mmHg, PaO 2 91 mmHg, and bicarbonate level 26 mmoL/L). Routine laboratory tests were within the normal range except for those listed in Table 1. Serum levels of neoplastic markers were within normal range, including carcinoembryonic antigen (2.7 ng/mL), prostate-specific antigen (3.75 ng/mL), and CA19.9 (15 U/ mL). Also the serum levels of angiotensin-converting enzyme (11 IU/mL) and β 2 microglobulin (2.50 mg/mL) were within normal limits. The pulmonary function tests showed the presence of a restrictive pattern with a vital capacity (VC) of 3.14 litres (70% of the predicted value), a forced vital capacity (FVC) of 3.11 litres (72% of the predicted value), forced expiratory volume in one second (FEV 1 ) of 2.55 litres (76.5% of predicted value), a FEV 1 /VC ratio of 81% (108% of the predicted value) and a total lung capacity (TLC), 5.35 litres (73.3% of the predicted value). DLCO was in the normal range ( Figure 1).
The chest radiography and a computed tomography of the chest (performed with iodine intravenous contrast medium) showed the presence of multiple bilateral pulmonary nodules (with a diameter variable between 3 mm and 3 cm) without contrast enhancement and the presence of one nodule (with the diameter of 2 cm) in the fourth hepatic segment showing late-phase contrast enhancement and another in the spleen (with the diameter of 1 cm) with cystic features ( Figure 2).
Interestingly, at the 18F-fluorodeoxyglucose positron emission tomography (PET), all these nodules were not showing any uptake of the tracer (Figure 3).
The fiberoptic bronchoscopy was normal. A transbronchial lung biopsy and an ultrasound-guided transthoracic lung biopsy were both nondiagnostic.
The final diagnosis of pulmonary epithelioid hemangioendothelioma was made by pulmonary wedge resection of a nodule located in the left lower lobe by video-thoracoscopic surgery. Histopathological examination of the resected tissue revealed round-to oval-shaped nodules, with a central sclerotic, hypocellular zone, and peripheral zone rich of cells. There was tumour diffusion into the adjacent bronchioles and the alveolar spaces with micropolypoid aspects. The ex- Immunohistochemical studies demonstrated that the neoplastic cells are endothelial cells immunoreactive for Von Willebrand factor, CD31, CD34, and vimentin ( Figure 4).
Case Reports in Medicine

Discussion
Pulmonary epithelioid hemangioendothelioma (PEH) is a rare, low-to intermediate-grade tumor of endothelial origin [1]. Epithelioid hemangioendothelioma can arise from many organs, including lungs, liver, bone, and soft tissue, simultaneously or sequentially. When this occurs, it may be difficult to determinate if the tumor is multicentric from the beginning or there is a primary lesion with metastases to the other tissues [4]. Around 120 cases have been reported in literature [2, Table 2], only five of them were in Italian patients [5,[15][16][17][18]. Mean (SD) age of patients is 40.1 (17.5) years, and 73% are females [6]. Interestingly, our patient is instead a 67-yearold male. Most patients are asymptomatic at presentation, and some are complaining of weight loss, fatigue, dyspnoea, fever, pleuritic chest pain, mild nonproductive cough, and haemoptysis [19]. In most cases, the physical examination is normal, but few cases of digital clubbing and pleural effusions have been reported [1,6].
The most characteristic feature of PEH on chest radiographs or CT is the presence of multiple perivascular nodules with well-or ill-defined margins in both lungs. The nodules may range in size up to 2 cm, but most of them are ≤1 cm in diameter; they are usually found near medium-sized vessels and bronchi [1]. This radiological presentation is suggestive of many lung diseases (Table 3).
Some authors consider 18F-fluorodeoxyglucose positron emission tomography an important tool for PEH diagnosis [7]; however, in our patient, the PET was negative, suggesting that a negative PET cannot exclude PEH. Unfortunately, we do not have a molecular explanation for this finding but may be related to a low proliferation rate of the neoplastic cells.
The diagnosis of PEH is made on the basis of the histopathological features and confirmed using immunohistochemical staining for endothelial cell markers, such as against factor VIII-related von Willebrand antigen, CD31 or CD34 [2,4,13,20,21].
The prognosis is variable. The 5-year survival is around 60% (range 47-71%). In fact, there are two groups of PEH at the clinical presentation: (1) one asymptomatic, with a solitary pulmonary nodule or unilateral multiple nodules. Usually they can be managed with surgery alone, and lymphatic invasion is unlikely. Their prognosis is good with a median survival of more than 10 years; (2) another symptomatic group presents with multiple bilateral pulmonary nodules or pleural effusion with scarce response to chemotherapy. The prognosis of this group is poor [11]. Most patients die from pulmonary insufficiency as a result of an increasing number of tumor nodules [9]. Hematogeneous metastases are rare and have been described especially in the liver but also in other sites [2,4].     The treatment of PEH is not standardized. Surgery alone is indicated in the presence of a single pulmonary nodule or unilateral multiple nodules. Lung transplantation should be considered in patients with vascular infiltration [10].
Various chemotherapies have been reported for unresectable or metastatic PEH, with variable effectiveness [22]. Other authors have suggested a role for the hormonal therapy (antiestrogens and progesterone) in patients with diffuse disease if the neoplastic cells express estrogen and progesterone receptors [23]. A slight regression of the pulmonary lesions was also obtained with interferon (IFN)-2α, probably for its antiangiogenic activity [24]. Thalidomide and IFN-α have also been proposed for unresectable cases [22]. Some beneficial results were also obtained with bevacizumab, a monoclonal antibody that blocks human VEGF-A [22,25]. The neoplastic cells express glucocorticoid receptors and the enzyme 11β-hydroxysteroid dehydrogenase involved in the synthesis of the steroids, suggesting a potential role for steroid modulators [26].
In conclusion, we had the opportunity to observe an unusual primary pulmonary hemangioepithelioma in an old 6 Case Reports in Medicine male patient, and interestingly, in comparison with the published literature, the neoplastic lesions were PET negative. Again, as previously suggested [27], we stress the importance of starting an international clinical registry of this unusual neoplasm.