A case report of retiform hemangioendothelioma as pleural nodules with literature review

Retiform hemangioendothelioma (RH) is a rare low-grade variant of angiosarcoma mostly reported on dermis or subcutaneously. A 30-year-old woman suffering from dry cough, dyspnea and pleural effusion has been described. Distinctive symptoms and lesions on high resolution computed tomography (HRCT) scan and common histological, immunological feature are discussed. Diagnosis was made by thoracoscopy as RH.


Background
RH is known as a rare kind of low-grade malignant angiosarcoma with high rate of local recurrence and low potential of metastasis which is a sparsely distributed disease counting 35 cases ( Table 1) whereas none of them is related to pleura or lung [1]. Given the lacking information of pleural RH, its clinical manifestation, HRCT presentation and thoracoscopic appearance of a female patient are presented. The definitive diagnosis was made due to pathological observation and immunochemical staining. The prognosis is unpredictable since the tumor can affect multiple organs [2]. Unfortunately, consensus has not been reached on if there is effective treatment to this tumor.

Clinical history and radiology
A 30-year-old female patient was admitted to pulmonary department because of dyspnea and dry cough denying chest pain, hemoptysis, fever, weight loss or other systemic symptoms. Her symptoms were stable and had not been given any medication prior to admission. Her chest X-ray by local hospital showed pleural effusion on the right side. She received modified radical mastectomy in 2006 removing a breast mass on her right chest. The biopsy confirmed a diagnosis of poorly-differentiated invasive ductal carcinoma with axillary lymph nodes metastasis therefore the patient received adjuvant chemotherapy and radiotherapy. Her father died of liver cancer. The rest of her personal history, social history and the review of systems were unremarkable. Decreased vocal fremitus and dullness of percussion on her right thorax were detected in physical examination. No enlarged superficial lymph nodes were palpated and laboratory tests revealed normal level of carcino-embryonic antigen (CEA). Her ultrasonic examination of abdomen and pelvis cavity alarmed no metastatic signs. The patient's HRCT results showed merely pleural effusion on the right side ( Fig. 1). No residual mass, enlarged lymph nodes of hilar or lesion on pleura were observed. Laboratory tests of her pleural effusion samples contained erythrocytes and leukocytes and it was exudates. Furthermore, cytological examination reported large amount of lymphocytes without atypical or carcinomatous cells. Scattered greyish variously sized nodes were discovered on costal pleura in thoracoscopy. The lesion presented themselves as exophytic masses surrounded by indistinctive borders with a tendency to fuse together. Pulmonary and diaphragmatic pleura were free from infiltration. Rechecking of chest X-ray complied with her former HRCT scan.

Histology and immunohistochemistry
Histological and immunological examination of biopsy specimen pictured disarranged, jagged, blood vessels of thin walls and slit-like fissures were prevailing. At higher magnification the vessels' walls were lined with highly nuclei/cytoplasm ratioed endothelial cells with minimal cytological atypia and mitosis. Atypical cells protruding into lumina mimicking "hobnail" appearance or endothelial papillae was absent as well as their invasion into adjacent tissues. Infiltration of lymphocytes was also rare (Fig. 2). Combined with immunohistochemical staining positive for CD31, CD34, D2-40 ( Fig. 3) and negative for CrebB-2, GCDFP-15, CEA, CA15-3, S-100, Ki-67 and myogenin, which confirmed the diagnosis and ruled out the possibility of breast cancer and other diagnosis, a diagnosis of RH was established.

Results
According to our knowledge and clinical experience, endostatin was recommended for treatment. The patient revisited 6 months later with relieved symptoms when her HRCT showed diminished and encapsulated pleural effusion after receiving symptomatic treatment and passed away at home in 2013.

Discussion
Hemangioendothelioma (HE), an intermediate lesion between hemangioma and angiosarcoma, has been incipiently delineated as a kind of vascular tumor highlighted by its marginal biological features [3]. It generally appears on skin or in soft tissues and extensively includes HE of epithelioid, kaposiform, retiform, composite and pseudomyogenic (also known as epithelioid sarcoma-like HE) subgroups and papillary intralymphatic angioendothelioma (also known as Dabska tumor). Malignancy of pseudomyogenic HE has recently been re-recognized [4]. Definitive diagnosis of varied types of this tumor is based on histopathlological morphology and immunohistochemical markers [5]. HE on Retiform hemangioendothelioma is a low-grade variant angiosarcoma which has been first introduced by Calonje in 1994 [6]. Hyperchromatic nuclei without mitosis suggests its intermediate characters [7] and indicates discrepant prognosis.
RH demonstrates a predilection for female adults [6]. The majority of RH cases have been described as lesions on trunk or limbs [8] whereas penis and scalp were occasionally involved [9]. Features of RH's lesion vary among individual patients expressing as masses, which is hyperhidrotic, or erosion [8,10,11]. Exophytic pattern seems to be more prevailing [8]. All the lesions in this patient were surrounded by "poor circumscription" as a presentation of its histological character.
Histological diagnosis lays the foundation of clinical diagnosis also plays the key role in differentiating RH from angiosarcoma and other subtypes of hemangioendothelioma. RH comprises of blood vessels "weaving a net" by infiltrating into bundles of collagen. Endothelial cells fashion intraluminal papillea with scarce cytoplasm [8,12]. However, pathological sample in this case for histological examination may accidentally be a single component of "composite hemangioendothelioma" which contains retiform HE, epithelioid HE, angiosarcoma, spindle cell hemangioma, lymphangioma, arteriovenous malformation [13] or part of these. This assumption is drawn from the fact that excision of gross sample has not be performed taking the fact that EH tends to form in lung into consideration [14].
Though histological and clinical features permits differential diagnosis between RH and other vascular tumors [20], it shares a number of similarities with hobnail hemangioma which has been considered as it benign counterpart. However, hobnail hemangioma features shortage of papillae protruding into lumina and restricted location [21] while prominent lymphatic infiltration and extensive lesion (dermis and subcutis) are widely applied to make the RH diagnosis [22]. Moreover, definitive diagnosis of a papillary lymphatic angioendothelioma with partial "netlike" camouflage and D2-40 positivity was in arguement [21].
The etiology of RH remains obscure. Latent relations between malignant medical history and RH should be elucidated [2,9]. In this case no evidence supports the internal link between RH occurence and the past radiotherapy.
No tumor-related [8] deaths in RHs are observed under the circumstance of low metastasis. However, a locally invasive RH in China and a metastatic RH in a six-year-old girl turned out to be lethal [23]. Although adjuvant immunotherapy and radiotherapy have been proved to be effective in several cases, none agreed tumor-responding treatments are recommended unless a complete surgical excision is performed [24][25][26][27]. Amanda and her colleagues, however, proposed specific appearance on dermoscopy as practical assistance to diagnosis and therapy [28].

Conclusions
In summary, a case of RH situating on pleura has been depicted which exhibited peculiar pathological, immunological features and lesions. It has been reported as intrathoracic nodules predisposing a patient to unilateral pleural effusion. However discussion has been placed on the causes and treatment of RH. It implies that RH on location other than skin or subcutis may lead to corresponding symptoms or even threatened survival.

Consent
Written informed consent was obtained from the patient for publication of this Case Report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.