Axillary fibromatosis with radiological-pathological correlation: a case report and literature review

Abstract

Background The term fibromatosis refers to a spectrum of soft tissue tumors resulting from the unbridled proliferation of fibroblasts, with high infiltrative power. It is a rare neoplasm, with an incidence of about 3 cases per million. Most common sites include the abdominal wall and cavity, chest wall, scapular area, and the limbs, rarely affecting the axilla. Imaging plays a major role in surgical planning and clinical follow-up. Differential diagnosis with other soft tissue tumors may be arduous, but a correct evaluation is fundamental. Case presentation A 33-year-old case is reported for the evaluation of a palpable hardened and immobile left axillary nodule. The ultrasound reveals a solid, elongated, heterogeneous, poorly delimited, infiltrative lesion observed in the left axillary hollow, with no detectable flow in the color Doppler mode. At magnetic resonance imaging, the same elongated and expansive lesion was better defined, revealing its irregular contours, alternating areas of hypo- and hyperintense on T2, heterogeneous enhancement, and no signs of signal decay on in- and out-of-phase sequences. Due to its growth and local invasion potential, surgical excision was performed. The microscopic analysis showed long and uniform spindle cell fascicles, with clear cytoplasm and wavy nuclei, arranged in different directions, included in collagen stroma. Immunohistochemistry was positive for nuclear beta-catenin, confirming the diagnosis of fibromatosis. Conclusion Imaging methods reflect the heterogeneous nature of the lesion. This study demonstrates the importance of using a multidisciplinary approach in addition to imaging tests and histopathological study for better diagnosis and therapeutic planning. The high infiltrative power always must be reminded of, since it affects young patients and diagnosis delay can lead to mutilating surgeries.