Epithelioid fibrous papule - a new variant

Area of Science:

• Dermatopathology
• Histology
• Oncology

Background:

• Fibrous papules (FPs) are common benign skin lesions, typically found on the nose.
• Several variants of FPs have been identified, including classic, hypercellular, clear cell, pigmented, pleomorphic, inflammatory, and granular types.

Purpose of the Study:

• To describe a novel variant of fibrous papules characterized by diffuse sheets of epithelioid cells.
• To differentiate this new variant from previously described types of fibrous papules, particularly clear cell variants.
• To investigate the immunohistochemical profile of these distinctive cells.

Main Methods:

• Histopathological examination of lesional skin biopsies.
• Immunohistochemical staining using procollagen and NKI/C3 antibodies.

Main Results:

• A distinct group of fibrous papules exhibited diffuse sheets of epithelioid cells, posing diagnostic challenges.
• Immunoperoxidase stains revealed that these cells were reactive for procollagen.
• The cells were negative for NKI/C3, distinguishing them from clear cell variants.

Conclusions:

• The 'epithelioid fibrous papule' represents a newly identified variant of fibrous papules.
• Its unique cellular morphology and immunohistochemical findings necessitate careful differentiation from other benign and malignant skin lesions.
• Further research may elucidate the specific cell lineage and behavior of this variant.