Clinicopathologic features of vulvar squamous cell carcinomas exhibiting prominent fibromyxoid stromal response.

The frequency, distribution, and significance of a prominent fibromyxoid stromal response to tumor was examined in 51 consecutive cases of invasive squamous carcinoma of the vulva in which the lesion was totally excised and follow-up information available. The stromal response consisted of an admixture of myxoid change and immature collagen with fibroblasts at the tumor-stromal junction and was focally (< 25% of tumor) in 11 of the 51 cases (21%), regionally (26-50% of tumor) in seven cases (14%), diffusely (> 50% of tumor) in eight cases (16%), and not at all in 25 cases (49%). Tumors showing a prominent fibromyxoid stromal response (> 25% of the tumor) were typically flat or elevated ulcerative lesions, whereas carcinomas without a prominent fibromyxoid stromal response were more commonly exophytic. Sixty percent of the tumors with a prominent fibromyxoid stromal response involved the clitoris, compared with clitoral involvement in only 14% of carcinomas without a prominent response. Case showing prominent fibromyxoid stromal response were associated with a significantly older age group, poorer survival rate, and more extensive lymph node metastases than when fibromyxoid stromal response was not prominent. This behavior was manifested despite the fact that these tumors were not larger, more deeply invading, of higher grade, or more likely to show infiltrating patterns of invasion than when fibromyxoid stromal response was not prominent. Because the ability of a tumor to invade is believed to be related in a large part to changes in the relationship of tumor to stroma, a correlation between fibromyxoid stromal response and aggressive tumor behavior would suggest that a specific pattern of alteration in the interaction of tumor cells with stroma occurs in a subset of vulvar squamous carcinomas. The current findings may reflect the diverse etiology of vulvar carcinoma. If the characteristic features of vulvar carcinomas showing a prominent fibromyxoid stromal reaction as shown in this study can be confirmed on larger study populations, "squamous cell carcinomas with prominent fibromyxoid stromal reaction" may be a useful designation for these tumors.