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Nodular fasciitis. Its morphologic spectrum and immunohistochemical profile
1Department of Soft Tissue Pathology, Armed Forces Institute of Pathology, Washington, D.C.
The American Journal of Surgical Pathology
|October 1, 1991
Summary
Nodular fasciitis (NF) is often misdiagnosed. Understanding its diverse morphology and characteristic immunohistochemical profile, which shows dual myofibroblastic and histiocytic markers, aids in accurate diagnosis and reduces sarcoma misclassification.
Area of Science:
- Pathology
- Oncology
- Dermatopathology
Background:
- Nodular fasciitis (NF) is a benign mesenchymal proliferation that can mimic sarcomas.
- Diagnostic challenges arise due to NF's varied histological presentations.
Purpose of the Study:
- To review the clinical, histological, and immunohistochemical features of nodular fasciitis.
- To identify key diagnostic markers that differentiate NF from sarcomas.
Main Methods:
- Retrospective analysis of 53 nodular fasciitis lesions.
- Evaluation of clinical presentation, histological morphology, and immunohistochemical staining.
- Comparison with sarcoma diagnoses.
Main Results:
- Nodular fasciitis exhibited a broad morphologic spectrum, including classic, granulation tissue-like, myofibroblastic, and ancient forms.
- Accurate diagnosis of NF was made in 43% of cases; sarcoma was diagnosed in 21%.
- Immunohistochemistry revealed a consistent profile: positive for smooth-muscle actin, muscle-specific actin, vimentin, and KP1 (histiocyte marker) in 92% of cases.
- Absence of keratin, S-100 protein, and desmin was noted.
Conclusions:
- Nodular fasciitis presents with diverse histological patterns.
- A characteristic immunohistochemical profile of dual myofibroblastic and histiocytic differentiation aids in distinguishing NF from sarcomas.
- Awareness of these features can decrease misdiagnosis rates.