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 of considerable clinical alarm. In the appropriate clinical setting, this lesion needs to be included in the differential diagnosis of solitary bone lesions, in particular when assessing the adequacy of a specimen at the time of aspiration.

CASE

A large, lytic mass on the posterior aspect of the sixth rib was incidentally discovered on a chest roentgenogram from a 46-year-old male during a routine presurgical evaluation for diverticulitis. The radiologic characteristics of the tumor were thought to be consistent with a neoplasm; that prompted a recommendation for fine needle aspiration biopsy (FNAB). The mass was thoroughly sampled under radiologic guidance, performing multiple aspirations of different areas. All smears prepared at the time of the aspiration for the evaluation of specimen adequacy showed abundant marrow tissue without any evidence of malignancy. Although it was initially thought that the tissue was probably obtained from the periphery of the lesion, this notion was discarded after multiple passes from different areas showed only marrow tissue and since there was radiologic evidence that the sample was obtained from within the lesion.

CONCLUSION

The diagnosis of FHH of the rib by FNAB or other small-biopsy techniques requires strict radiologic-pathologic correlation. Awareness of this entity will avoid unnecessary repeated biopsy procedures and potentially large, complicated surgical procedures. This case shares several features with the other two reported cases: a solitary lesion on the rib presenting in an asymptomatic patient with no evidence of associated hematologic disease.