Cytopathological findings of intranodal palisaded myofibroblastoma: Case report and review of the literature.

INTRODUCTION: Intranodal palisaded myofibroblastoma (IPM) is an exceedingly rare benign mesenchymal tumor of the lymph nodes. Magnetic resonance imaging (MRI) findings are unspecific, which may present diagnostic challenges to fine-needle aspiration cytology (FNAC). The histological and immunohistochemical features of IPM are unique.

CASE REPORT: A previously healthy 40-year-old male patient presented a slow-growing solitary left inguinal mass. FNAC revealed clustered cells within a metachromatic stroma, single spindle cells without atypia, hemosiderin pigment, and siderophages. An MRI showed a central hyperintense septum in fat-suppressed, T2-weighted sequences. The excised lymph node contained central haphazard fascicles of spindle cells with focal nuclear palisading, hemosiderin pigment, extravasated erythrocytes, and hemorrhagic areas. Vimentin and smooth muscle actin were diffusely positive. Amianthoid collagen fibers were not clearly observed.

CONCLUSION: IPM is an extremely rare mesenchymal benign intranodal tumor that should be included in the differential diagnosis of spindle cell lesions in the inguinal region.