Abstract
Masson’s tumor, also known as intravascular papillary endothelial hyperplasia (IPEH), is a rare benign vascular lesion characterized by an abnormal proliferation of endothelial cells within blood vessels, forming papillary structures that can occur in various parts of the body, including the parotid gland. Masson’s etiology and risk factors remain unclear, but trauma and vascular pathological conditions may contribute to tumor progression. Despite its benign nature, Masson’s tumor can present diagnostic challenges due to its variable clinical presentation and the need to differentiate it from other vascular lesions and malignancies. This case report presents a rare occurrence of Masson’s tumor in the parotid gland of a 39-year-old female patient, along with a comprehensive review of the existing literature of this unusual presentation.
Highlights
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Masson’s tumor of the parotid gland is a rare clinical entity.
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Masson’s tumor, also known as intravascular papillary endothelial hyperplasia (IPEH), is a benign vascular lesion characterized by an abnormal proliferation of endothelial cells within blood vessels.
1
Introduction
Masson’s tumor, or intravascular papillary endothelial hyperplasia, is a non-neoplastic vascular lesion characterized by reactive endothelial cell proliferation. It is often misdiagnosed due to its rarity and similarities to malignant vascular tumors such as angiosarcoma [ ]. Masson’s tumor etiology is indistinct and is a multifactorial disease [ ]. Tumors can be triggered by local trauma and vascular conditions such as hemangiomas, blood stasis, and pyogenic granulomas; nevertheless, in almost 70 % of cases, the causes and stimulating factors are still unknown [ ]. While commonly found in the skin and subcutaneous tissues, occurrences in the parotid gland are exceedingly rare [ ]. This report aims to document a new case of Masson’s tumor in the parotid gland and review literature to provide insight into its clinical presentation, diagnosis, and management.
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Case report
A 39-year-old female presented with a painless, gradually enlarging mass in the right parotid gland over 9 months period. On palpation, the mass was soft, mobile, and non-tender. There were no signs of facial nerve involvement or regional lymphadenopathy. A CT neck with contrast revealed a 4 x 2.3 × 2 cm well-defined lesion within the superficial lobe of the right parotid gland ( Fig. 1 ). Fine-needle aspiration cytology (FNAC) suggested a benign lesion. A subsequent complete excision of the mass via superficial parotidectomy was performed. Of note, at the end of the excision, significant bleeding was encountered. However, it was carefully controlled by bipolar electrocautery and surgical clips to obtain hemostasis and avoid any damage to the facial nerve. Histopathological analysis revealed a lesion composed of proliferating endothelial cells forming papillary structures within a vascular lumen, consistent with intravascular papillary endothelial hyperplasia ( Fig. 2 ). The postoperative course was uneventful, and there was no evidence of recurrence at a six-month follow-up.
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Discussion
Masson’s tumor, also known as intravascular papillary endothelial hyperplasia (IPEH), was initially reported by Pierre Masson, a French pathologist in 1923 [ ]. It is a benign vascular lesion resulting from an exaggerated endothelial proliferation within blood vessels, often following trauma or thrombosis [ ]. He identified a distinct form of benign vascular tumor that was characterized by an overgrowth of endothelial cells forming papillary structures within blood vessels [ ]. The tumor typically had a well-defined structure with minimal atypia and endothelial proliferation that occurred within the lumen of blood vessels [ ].
The condition is classified into three distinct types: primary (pure), secondary (mixed), and extravascular [ ]. The primary type arises de novo within a vessel, whereas the secondary type develops within pre-existing vascular lesions like hemangiomas, and the third type is an extravascular type occurs outside the vessel, typically in hematomas [ ]. The specific etiology of Masson’s tumor remains poorly comprehended [ ]. It is believed to result from a reactive process to vascular stasis or thrombosis, leading to endothelial proliferation [ , ]. The histological characteristics of the disease may lead to confusion with angiosarcoma; however, it may be differentiated by the absence of abnormal cell divisions and a reduced ratio of nucleus to cytoplasm [ , ].
Masson’s tumor often manifests as a gradually growing, painless mass [ , ]. If it appears in the parotid gland, it could resemble other tumors in the salivary glands, whether they are benign or malignant [ , ]. Imaging studies typically show a well-circumscribed, enhancing mass, but a definitive diagnosis relies on histopathological examination [ ].
Although uncommon, the occurrence of Masson tumor in the head and neck has been reported in different literature. Corio et al. identified 14 cases of Masson’s tumor in the head and neck area, of which only one case was in the parotid gland [ ]. The first well documented reported case report of Masson’s tumor in the parotid gland was reported by Carta et al. [ ]. It presented in a 43-year-old female patient with a 4-year history of right parotid gland swelling and had characteristic histopathological appearance of a vascular cavity containing an organized thrombus and a single layer of epithelium without mitotic figures [ ]. The authors reported no recurrence following subtotal parotidectomy after 30-month follow up [ ]. Mohebbi et al. reported a case of Masson’s tumor in the parotid gland in a 29-year-old female that presented with a 12-year history of slowly enlarging parotid mass [ ]. It was treated by embolization followed by a total parotidectomy with uncomplicated post operative course [ ]. Moreover, Magnogna et al. reported a case of IPEH in a 70-year-old woman with a 5-year duration of right painless parotid enlargement. Initial imaging revealed hyperintensity with homogenous contrast enhancement and was consistent with pleomorphic adenoma. Histological examination was consistent with IPEH and the morphological diagnosis was type III variant [ ]. Mokhtari et al., reports one case of IPEH in parotid gland in a 39-year-old male, that like other cases, presented as a painless left parotid swelling [ ]. It was treated with a partial parotidectomy with no reported post operative complications [ ]. In our case, the preoperative work up didn’t reveal Masson’s tumor, the tumor was excised via superficial parotidectomy without preoperative embolization. Table 1 summarize all the reported cases of Mansson’s tumor in the parotid gland.
