Clinical and histological patterns of dermatofibroma without gross skin surface change: A comparative study with conventional dermatofibroma

Abstract

Background: Dermatofibroma sometimes clinically presents as a nodular lesion without gross skin surface change. Clinicopathologic features of this variant of dermatofibroma have not been evaluated.

Aims: To assess clinicopathologic features of dermatofibroma presenting as a subcutaneous nodule.

Methods: This study reviewed the clinical and histological features of 42 cases of subcutaneous dermatofibromas and compared them with 95 cases of conventional dermatofibroma.

Results: Dermatofibroma without gross skin surface change was associated with a shorter pre-diagnosis duration than conventional dermatofibroma. Increase in size during the pre-diagnosis period was significantly more frequent in the conventional type. In addition, these dermatofibromas were more likely than the conventional type to occur in the head and neck region. Although tumor depth was deeper than in the conventional type, less than half of the dermatofibromas without gross skin surface change were found histologically to be "subcutaneous" or "deep-penetrating dermatofibroma". Subcutaneous extension was more frequent in these dermatofibromas while focal stromal hyalinization and hemosiderin deposits were more common in the conventional type.

Limitations: This study is a retrospective, single center design.

Conclusion: The present study suggests that dermatofibroma without gross skin surface change is a variant type with distinct clinical and histological features that distinguish them from conventional dermatofibroma.