FOCAL HEMATOPOIETIC HYPERPLASIA OF THE RIB - REPORT OF A CASE DIAGNOSED BY FINE-NEEDLE ASPIRATION

BACKGROUND: Focal hematopoietic hyperplasia (FHH) of the rib is a rare , benign, localized proliferation of bone marrow to such a degree that it produces a tumorlike expansion of the rib that can be the source o f considerable clinical alarm. In the appropriate clinical setting, th is lesion needs to be included in the differential diagnosis of solita ry bone lesions, in particular when assessing the adequacy of a specim en at the time of aspiration. CASE: A large, lytic mass on the posteri or aspect of the sixth rib was incidentally discovered on a chest roen tgenogram from a 46-year-old male during a routine presurgical evaluat ion for diverticulitis. The radiologic characteristics of the tumor we re thought to be consistent with a neoplasm; that prompted a recommend ation for fine needle aspiration biopsy (FNAB). The mass was thoroughl y sampled under radiologic guidance, performing multiple aspirations o f different areas. All smears prepared at the time of the aspiration f or the evaluation of specimen adequacy showed abundant marrow tissue w ithout arty evidence of malignancy. Although it was initially thought that the tissue teas probably obtained from the periphery of the lesio n, this notion was discarded after multiple passes from different area s showed only marrow tissue and since there tons radiologic evidence t hat the sample was obtained from within the lesion. CONCLUSION: The di agnosis of FHH of the rib by FNAB or other small-biopsy techniques req uires strict radiologic-pathologic correlation. Awareness of this enti ty will avoid unnecessary repeated biopsy procedures and potentially l arge, complicated surgical procedures. This case shares several featur es with the other two reported cases: a solitary lesion on the rib pre senting in an asymptomatic patient with MO evidence of associated hema tologic disease.