Pleomorphic dermal sarcoma: adverse histologic features predict aggressive behavior and allow distinction from...

Area of Science:

• Dermatopathology
• Surgical Oncology
• Oncologic Pathology

Background:

• Atypical fibroxanthoma (AFX) is generally considered benign when strict diagnostic criteria are met.
• Tumors with similar histology but exhibiting deep invasion, necrosis, or vascular/neural involvement are classified differently, often as pleomorphic dermal sarcoma (PDS) or undifferentiated pleomorphic sarcoma of the skin.
• The characteristics and clinical behavior of this PDS group are not well-defined in existing literature.

Purpose of the Study:

• To comprehensively investigate the clinical and pathological spectrum of pleomorphic dermal sarcoma.
• To identify key histological features associated with adverse outcomes in tumors resembling AFX.
• To better define the characteristics of PDS to improve diagnostic accuracy and patient management.

Main Methods:

• Retrospective review of 32 cases of pleomorphic dermal sarcoma from departmental archives.
• Detailed analysis of clinical presentation, including patient demographics, tumor location, and size.
• Comprehensive histopathological examination, including assessment of invasion depth, necrosis, lymphovascular invasion, perineural invasion, cellular composition, mitotic activity, and immunohistochemical profiling.
• Correlation of histological findings with clinical follow-up data, including recurrence and metastasis rates.

Main Results:

• The study included 32 PDS cases, predominantly affecting elderly men on sun-damaged skin (median age 81 years), with a predilection for the head (median tumor size 25 mm).
• Histologically, tumors showed deep subcutaneous, muscular, or fascial invasion, often ulcerated, poorly marginated, and asymmetrical.
• Adverse features were common: necrosis (53%), lymphovascular invasion (26%), and perineural invasion (29%). Immunohistochemistry showed variable expression of smooth muscle actin (70%) and CD31 (48%), with CD10 expressed in all cases.
• Follow-up (median 24 months) revealed local recurrence (28%) and metastasis (10%), primarily to the skin, with no disease-related mortality observed.

Conclusions:

• Adverse histological features, specifically deep subcutaneous invasion, tumor necrosis, and perineural/lymphovascular invasion, are critical indicators of malignant potential in tumors that may otherwise resemble atypical fibroxanthoma.
• Accurate recognition of these features is essential for distinguishing PDS from benign lesions and for predicting patient prognosis.
• This study highlights the importance of careful histopathological evaluation and emphasizes the low-grade malignant potential associated with these specific adverse findings.