Figure 1: Many variable blood vessels separated by fibromyxoid stroma (H&E; x200).
Figure 2: Presence of stellate cells, spindle cells and lymphocytes in the stroma (H&E; x400).
Superficial angiomyxomas in the parotid region are extremely rare. Rodriguez et al have previously reported one such case in the parotid region in a 61-year-old male [6].
The differential diagnosis includes benign and lowgrade malignant myxoid lesions including aggressive angiomyxoma, focal cutaneous mucinosis, myxoid neurothekeomas, myxoid neurofibroma, acral fibromyxoma and myxoid liposarcoma [7]. It is important to differentiate it from these lesions since superficial angiomyxoma has a propensity for local recurrence.
Aggressive angiomyxoma is larger, situated deep, usually in the female pelvis and the blood vessels are large, thick walled and prominent. Focal cutaneous mucinosis lacks lobular architecture, epithelial structures and neutrophils in the stroma. Superficial acral angiomyxoma is almost exclusively found on the fingers and toes in middle age and lacks a neutrophilic infiltrate [8]. Myxoid neurothekeoma has a prominent lobular growth pattern and is characterized by plump cells that are S-100 positive. Myxoid neurofibroma has cells with buckled nuclei that are S-100 positive. Myxoid liposarcomas are deeply situated and larger with chicken wire vascular pattern and lipoblasts. Myxofibrosarcoma has more marked nuclear atypia and hyperchromasia with presence of curvilinear blood vessels lined by cells with hyperchromatic nuclei [7].
At this site, the differential diagnosis includes parotid gland tumors as well as cysts of the first branchial arch [5]. Fine needle aspiration cytology can be confusing as in our case.
Superficial angiomyxomas have an overall good prognosis as these lesions remain superficial without affecting deeper structures. Appropriate diagnosis, complete surgical treatment and close follow up are advised.
In conclusion, the case highlights the importance of distinguishing superficial angiomyxomas from other lesions that occur in the parotid region. One should be cautious about reporting pleomorphic adenoma on smears showing abundant fibromyxoid stroma.
CONFLICT OF INTEREST
The authors declared no conflict of interest.
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