Deep penetrating dermatofibroma versus dermatofibrosarcoma protuberans. A clinicopathologic comparison

Area of Science:

• Dermatopathology
• Oncology
• Immunohistochemistry

Background:

• Deep penetrating dermatofibroma (DPDF) and dermatofibrosarcoma protuberans (DFSP) are distinct cutaneous neoplasms.
• Accurate differentiation is crucial for appropriate clinical management.

Purpose of the Study:

• To elucidate the distinct clinical, histological, and immunohistochemical features of DPDF and DFSP.
• To identify reliable diagnostic criteria for differentiating these entities.

Main Methods:

• Comparative analysis of 20 DPDF and 14 DFSP cases.
• Evaluation of clinical presentation, histological patterns, and immunohistochemical markers (CD34, factor XIIIa, HHF35, metallothionein).
• Multivariate analysis to determine the most valid diagnostic criteria.

Main Results:

• DPDF typically presents as a nodule on limbs, while DFSP occurs as plaques/nodules on the trunk.
• Histologically, DPDF shows regular nodular/scalloped margins with sclerosis, whereas DFSP infiltrates fat in a lacelike pattern without sclerosis.
• Immunohistochemistry reveals DPDF is negative for CD34 but positive for factor XIIIa, HHF35, and metallothionein (MT); DFSP is positive for CD34 and negative for factor XIIIa, HHF35, and MT.
• Sclerosis and MT labeling are highly significant (p=0.0001) for DPDF diagnosis.

Conclusions:

• DPDF and DFSP exhibit distinct clinical, histological, and immunohistochemical profiles.
• The combination of sclerosis and MT expression is a highly reliable method for differentiating DPDF from DFSP.
• These findings aid in accurate diagnosis and patient management.