Angiomyxolipoma of the Cheek: A Rare Oral Tumour

Abstract

Angiomyxomas, also known as vascular myxolipomas, are a rare type of soft tissue tumor characterized by the proliferation of adipose tissue within a myxoid stroma accompanied by multiple vascular channels. They represent a distinct variant of lipomas and require differentiation from other benign and malignant lipoma subtypes. Despite their rarity, only a few cases of angiomyxolipoma have been documented in medical literature. We present a case of angiomyxolipoma occurring in the cheek of a 40-year-old female patient who presented with a long-standing history of swelling on the left side of her face. Histopathological examination revealed alternating nests of myxoid and adipose tissue containing dilated blood vessels, which confirmed the diagnosis of angiomyxolipoma. This case underscores the importance of recognizing and accurately diagnosing rare soft tissue tumors like angiomyxolipoma to guide appropriate management and follow-up care.

Introduction

Lipomas are the most commonly encountered mesenchymal tumors. Within the oral cavity, they are categorized histologically into classic, spindle cell/pleomorphic, fibrolipoma, or chondroid lipomas [1, 2]. Angiomyxolipoma, initially identified by Mai et al. [3]. ,represents a rare variant distinguished by mature adipocytes interspersed with myxoid areas and numerous vascular channels. Despite its uniqueness, only a handful of angiomyxolipoma cases have been documented. Instances specifically involving the cheek and oral cavity are even more infrequent. In this case report, we aim to delineate the notable clinical and pathological characteristics of angiomyxolipoma, highlighting its relevance as a differential diagnosis for cheek swellings. We will discuss its histopathological features, management strategies, and follow-up protocols.

Case Report

A 40-year-old female patient presented to our outpatient department with a 1-year history of a slowly growing, painless swelling on the left side of her cheek (Fig. 1). The swelling started gradually and had been increasing in size over the past year. She reported no other symptoms and had no underlying health conditions. Upon physical examination, a solitary, mobile swelling measuring 6 × 4.5 cm was observed. It was relatively well-demarcated, with a texture ranging from soft to firm, and had a smooth surface. There were no changes in the color or texture of the overlying skin or mucosa. Examination of the oral cavity revealed a slight bulge in the buccal mucosa beneath the swelling. There was no palpable enlargement of cervical lymph nodes.

Fig. 1.

Patient presented with painless left sided cheek swelling

Subsequently, an ultrasound scan was performed, revealing a subcutaneous swelling situated superficially to the masseter muscle. Fine needle aspiration cytology (FNAC) of the mass indicated the presence of myxoid components and was initially reported as Myxoma. Following this, the decision was made to surgically remove the swelling. The excision was carried out via an intraoral approach under general anesthesia (Fig. 2). A curvilinear incision of approximately 4 cm was made on the buccal mucosa. The swelling was identified, dissected free from its attachments, and removed through the incision. The excised specimen measured approximately 6 × 4 cm and was sent for histopathological examination (Fig. 3).Histopathological analysis of the specimen revealed mature adipose tissue interspersed with numerous thin- and thick-walled blood vessels, along with areas of interstitial hemorrhage. The intervening stroma exhibited myxoid changes (Fig. 4). Based on these findings, a histological diagnosis of angiomyxolipoma was established.

Fig. 2.

Intra-operative picture showing the tumor (white arrow) being excised intra-orally

Fig. 3.

Surgical specimen after excision

Fig. 4.

Angiomyxolipoma histological picture A- Tumor composed of adipose tissue separated by fibrous septa (H&E; 40x), B- Numerous thin- and thick- walled blood vessels found in the adipose tissue (H&E; 100x), C- Mature lipomatous tissue in a myxoid stroma (H&E; 200x), D- Myxoid stroma showing abundant mucin (H&E; 40x), E- Myxoid stroma with areas of interstitial hemorrhage (H&E; 40x), F- Spindle cells in myxoid stroma without any aytpia (H&E; 200x)

The patient experienced a smooth recovery following surgery, with only mild cheek swelling noted for a few days postoperatively. There were no other complications, and she was discharged on the fifth day after surgery. Since then, the patient has been undergoing regular follow-up for the past year, during which no recurrence of the swelling has been observed. This indicates a favorable outcome following excision of angiomyxolipoma. Regular monitoring will continue to ensure ongoing health and to detect any potential recurrence promptly.

Discussion

Adipose tissue tumors are the most common type of mesenchymal growths, but they include rare variations. Lipomas, which can vary depending on their location and the presence of other tissue types, encompass several subtypes such as synovial, parosteal, intraosseous, lumbosacral, and thymolipoma. Additionally, there are variants like spindle cell/pleomorphic, chondroid, and lipomas that incorporate elements such as angio-, fibro-, myxo-, chondro-, osteo-, and myolipoma. Each subtype exhibits distinct histological characteristics and clinical manifestations based on their specific tissue composition and anatomical site.

According to Furlong et al. [2], in the series of 125 lipomas studied by him, the most frequent types found were the classic type and the spindle cell/pleomorphic lipoma (SCL) (49.6 and 47.2%, respectively). In 1996, Mai et al. [3] reported a case of a rare variant of lipoma of the spermatic cord in a 34 year-old man, characterized by a proliferation of adipocytes associated with a myxoid background and multiple blood vessels and first designated it as angiomyxolipoma. Since then, ten cases of this rare variant have been reported in the literature [3–11], out of which only one case of intraoral angiomyxolipoma has been reported till date [12].

Angiomyxolipomas can occur in various soft tissue locations across the body, with documented cases in the head and neck, extremities, abdominal wall, thigh, and scrotum [13]. These tumors are typically benign and are characterized by their unique histological features, including a mix of adipose tissue, myxoid matrix, and vascular channels. They usually presents as a soft to firm, well circumscribed swelling. When it presents in the head and neck, it is very difficult to arrive at an exact clinical diagnosis. Diagnosis is often also missed after a fine needle aspiration cytology (FNAC) also, as in our case. FNAC is subject to sampling error, interpretation of pleomorphic cells is difficult, and there is a risk of severe hemorrhage [14]. Thus, unfortunately, making a diagnosis by aspiration biopsy and cytology is least reliable. A definitive diagnosis is more often obtained during the histopathological examination of the excised specimen. This case report shows the broader nature of differential diagnosis in cases of a cheek swelling and the problems in reaching a final diagnosis without an excision biopsy. Excision of the entire tumor is a reliable method of treatment for angiomyxiolipoma of the cheek. In smaller swellings even intra-oral route of excision suffices. Long term follow up is important as recurrences are known occur even after many years.

On gross examination, the cut surface of the lesions appears yellowish and myxoid. Microscopically, there is a combination of mature adipose tissue, a myxoid matrix containing stellate cells, and a prominent vascular network. The background also shows a mild mixed inflammatory infiltrate.

The histopathologic features of angiomyxolipoma are characteristic and include an admixture of a myxoid area with relatively few cells, mature adipose tissue without lipoblasts, and numerous thin- and thick-walled vascular structures. Angiomyxolipoma (AML) shares histological similarities with several other tumors, necessitating consideration of various differential diagnoses. These include spindle cell lipoma/pleomorphic lipoma (SPL), chondroid lipoma, myxolipoma, angiolipoma, dendritic fibroangiolipoma, myolipoma, angiomyolipoma, superficial angiomyxoma, angiomyofibroblastoma, cellular angiofibroma, lipoblastoma, low-grade myxofibrosarcoma, and myxoid liposarcoma. Additionally, non-lipomatous conditions like myxoid neurofibroma should also be considered.Another differential diagnosis to be mindful of is myxoid fibrolipoma, which is more common in the head and neck areas of men. It can be differentiated from AML by its lack of a prominent vascular network and the presence of a dense fibrous stroma. These distinctions are crucial for accurate diagnosis and appropriate management of patients presenting with similar clinical features [15].

Histological features, such as presence/absence of vascular structures, spindle cells and pleomorphic cells (floret-like cells) are diagnostic criteria for differential diagnosis of angiomyxolipoma from lesions like spindle cell/pleomorphic lipoma(SCL). The absence of necrosis, cellular pleomorphism, lipoblasts and atypical mitoses observed within adipose tissue may aid in differentiating angiomyxolipoma from malignant lesions, such as myxoidliposarcoma and low-grade myxofibrosarcoma [3, 15].

Angiomyxolipomas (AMLs) can be distinguished from low-grade myxofibrosarcoma by their lack of cellular pleomorphism, nuclear atypia, hypercellularity, and hypervascularity. Similarly, they differ from myxoid liposarcoma and lipoblastoma due to the absence of lipoblasts, a chicken wire capillary network, necrosis, and a low Ki67 labeling index. Myxoid neurofibromas are excluded based on the negative expression of S100P by the stromal cells.

On immunohistochemistry (IHC), the mature adipocytic component of AML shows positivity for S100P, whereas the stromal cells are negative. The rich vascular network stains positively for CD31 and CD34. Among the reported cases, 15 out of 21 showed CD34 positivity in the stromal cells. However, studies by Hattori and Billings et al. indicate that CD34 negativity in stromal cells rules out the possibility of spindle cell lipomas (SPLs), thereby suggesting that AMLs typically have CD34-negative stromal cells. All reported cases of AML to date have had a Ki67 labeling index of less than 5% and were negative for HMB45 [16].

In summary, we report a rare case of angiomyxolipoma located in the head and neck region. This benign lesion is characterized by a proliferation of vascular vessels, a notable presence of both mature and immature adipocytes intertwined with abundant myxoid components. It is crucial to distinguish this entity from other benign and malignant lesions of the oral cavity.We underscore the importance of excision biopsy in diagnosing angiomyxolipoma, as fine needle aspiration cytology may not always provide a definitive diagnosis. Excision biopsy allows for thorough histopathological examination, which is essential for accurately identifying and categorizing this rare tumor type.

Funding

This study did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.

Declarations

Ethical approval

This study has been carried out in compliance with the ethical standards after obtaining Institutional Ethics Committee Approval (Manipal Academy of higher Education- Kasturba Medical College, Mangalore).

Informed consent

I hereby give my consent for images or other clinical information relating to my case to be reported in a medical publication. I understand that my name and initials will not be published and that efforts will be made to conceal my identity, but that anonymity cannot be guaranteed. I understand that the material may be published in a journal, web site or other form of publication. As a result, I understand the material may be seen by the general public. I understand that the material may be included in medical books.

Conflict of interest

Not applicable.