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Confusing nomenclature can put patients at risk. Atypical fibroxanthoma (AFX) is a low-grade malignancy of the dermis associated with minimal risk. Pleomorphic dermal sarcoma (PDS) likewise involves the dermis but also invades subcutaneous tissue and carries a slightly higher risk of recurrence and metastasis. Undifferentiated Sarcoma (also commonly called malignant fibrous histiocytoma) arises in deeper soft tissues and has a dismal prognosis. The cells of all these tumors look identical microscopically. Confusing these terms can result in unnecessary radical surgery, radiotherapy, and even chemotherapy in some cases. Psychological sequelae from incorrectly assigning a highly malignant diagnosis can also be devastating.

A 62-year-old man with a history of multiple previous skin cancers presented with an enlarging ulcerated tumor on the scalp measuring 3 cm in its greatest clinical dimension. A superficial biopsy had been performed and the histopathology revealed a tumor composed of highly atypical pleomorphic tumor cells with sarcomatoid features. No in situ disease was evident in the epidermis. Immunohistochemistry (IHC) was performed on the biopsy and revealed no evidence of squamous differentiation (CK5/6, p63), melanocytic differentiation (Sox-10, Melan-A), vascular differentiation (CD31), or smooth muscle differentiation (desmin). A diagnosis of AFX was made.

This patient was referred for margin control surgery (MCS), but the initial slides were not available for review. A biopsy was performed on the day of surgery and examined fresh with frozen sections (Fig. 19.1). The pathology matched that described in the biopsy report, i.e., the tumor was undifferentiated and pleomorphic. The tumor was overt histopathologically so not challenging to see in the frozen section slides and therefore a good candidate for intraoperative margin assessment.


A biopsy on the day of surgery showed a highly atypical pleomorphic tumor without clear differentiation consistent with the referred diagnosis of AFX. Intraoperative biopsy is helpful as it offers a glimpse of the expected morphology in the margin evaluation.

MCS proceeded and evaluation of the entire margin was performed with the en face 3D technique (see Chap. 6). The radial margins were clear, but the tumor was noted to extend deep into subcutaneous adipose tissue (Fig. 19.2). This is a feature not typically seen in AFX and generally suggests a diagnosis of PDS.


During intraoperative frozen section examination of the margins, it was noted that the tumor extended deeply into subcutaneous tissues. This is not a feature typically seen in AFX and suggests a diagnosis of PDS.

Given the unusual deep involvement, the tissue excised in the first level and frozen for margin assessment was placed in formalin and sent to the pathology laboratory for paraffin processing as a debulk specimen.

The entire tumor was cleared with the second level which included an excision down to pericranial tissue ...

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