Abstract
Venous malformations are slow-flow lesions characterized by an abnormal venous network. Forty percent of these lesions occur in the head and neck, and they usually present in childhood or early adulthood. 1 They may present after expansion caused by trauma, incomplete surgical resection, 1 or a change in hormone levels. Often, the overlying skin takes on a bluish tinge that makes the diagnosis more apparent. However, a deeper malformation occasionally may simply distort the overlying tissues, giving the impression of a tumor or other growth.
Magnetic resonance imaging (MRI) of venous malformations may show phleboliths, calcifications commonly found in venous malformations. However, parotid sialoliths may similarly appear on imaging as hyperdense structures in the facial region. Therefore, adjunctive diagnostic measures may be required. Presented here are two cases of venous malformations of the parotid gland, initially misdiagnosed on imaging.
The first patient was a 30-year-old woman who presented with a several-month history of a parotid mass. She was asymptomatic but noted a cosmetic deformity. Examination confirmed the presence of a posterior parotid mass. In preparation for surgery, fine-needle aspiration (FNA) and MRI were ordered. The FNA returned with scant cellularity. The MRI confirmed the presence of a superficial parotid mass with a central hypointensity, thought to be a calcification or sialolith (figure 1).
Patient 1. MRI shows a parotid mass with a central hypointensity. This later was shown to be a venous malformation with a phlebolith.
The decision was made to proceed with an operative excision. During operative exploration, no palpable mass was found. The radiology studies were reexamined, and the interpreting radiologist was called intraoperatively to discuss the case. After lengthy discussion, the possibility of a venous malformation was entertained. Minimal further operative exploration confirmed this to be the case, and the procedure was terminated.
The second case involved a 46-year-old woman who presented with a long-standing history of parotid disease. She had undergone a cyst removal 30 years earlier and had undergone an external procedure 20 years earlier to remove sialoliths. This procedure was terminated without removal of all stones because of bleeding.
This patient presented now with recurrent, painful sialolithiasis of the parotid, confirmed on computed tomography (CT), but her unusual history suggested the need for further imaging. An MRI scan revealed the presence of an “infiltrative mass of the anterior parotid gland.” The differential diagnosis included a malignancy or neurofibroma. However, careful examination of both studies led us to suspect a venous malformation; therefore, magnetic resonance venography (MRV) was ordered. Although this was not diagnostic, a low-flow lesion was suggested by late-phase venous contrast enhancement in the right face (figure 2). The diagnosis of venous malformation was made, and the patient is being observed.
Patient 2. MRV shows late-phase venous enhancement of the right face.
These cases illustrate an important point, that imaging can result in misdiagnoses because imaging characteristics of parotid masses and venous malformations overlap. 2 Therefore, clinical suspicion must always remain high, particularly when operative findings do not correlate with imaging and when extensive surgery carries the risk of morbidity.