# Atypical Fibroxanthoma/Pleomorphic Dermal Sarcoma With Osseous Metaplasia: A Series of Three Cases

## TL;DR

This paper reports three rare cases of skin tumors with bone-like features in elderly patients, emphasizing the need for accurate diagnosis to avoid misidentification.

## Contribution

The novelty lies in presenting three new cases of AFX/PDS with osseous metaplasia, a rare feature previously reported in only one case.

## Key findings

- AFX/PDS cases with osseous metaplasia occurred in elderly patients with no recurrence or metastasis.
- Osseous metaplasia in AFX/PDS is rare and can lead to diagnostic confusion with other bone-forming tumors.
- Accurate diagnosis is crucial due to overlapping features with other tumors.

## Abstract

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are rare mesenchymal tumors typically arising on sun‐damaged skin of the head and neck in elderly patients. PDS is a more aggressive tumor but with similar demographics, cellular morphology, immunohistochemical features, and genetic findings. The histopathologic diversity and lack of specific immunohistochemical markers for these entities increase the risk of misdiagnosis. To our knowledge, osteoid matrix production has been noted previously in only one case of PDS. We present three additional cases of AFX/PDS with osseous metaplasia, all of which were from the head of elderly patients (91–93 years old). No case recurred or metastasized, thus underscoring the importance of distinguishing this entity from other primary or metastatic tumors with osseous differentiation or metaplasia.