Fine needle aspiration cytology of fibrous hamartoma of infancy

BACKGROUND: Fibrous hamartoma of infancy (FHI) is an uncommon, benign lesion with a distinctive histologic appearance, usually occurring as a small, rapidly growing soft tissue swelling developing in the first two years of life. Apart from one publication, there appear to be few descriptions of the fine needle aspiration biopsy (FNAB) features of this lesion. Detailed information on the clinical and FNAB findings in a patient with FHI is presented. CASE: An 8-month-old female had a firm mass on the posterior aspect of the arm. FNAB produced smears that displayed moderate cellularity, loosely lying and clustered fibroblastic-appearing cells, fatty tissue and collagenous material without evidence at significant nuclear atypia or mitoses. CONCLUSION: In the appropriate clinical setting, if the pathologist performing the microscopic evaluation can be confident that all the tissues with features as described are exclusively from the nodule, it is likely that a confident diagnosis of FHI can be made.