Fine needle aspiration cytology of Gouty Tophi with review of literature

Gouty tophi presenting as multinodular lateral inguinal swelling: A case report

Fine-needle aspiration cytology (FNAC) is an important diagnostic tool which is replacing biopsy for the diagnosis of subcutaneous nodules. We present a case of 75 years old female with right sided multinodular lateral inguinal swelling since 2 years, without any clinical features of arthritis. FNAC of the lesion revealed negatively birefringent, long needle shaped monosodium urate crystals in the background of amorphous granular debris. Further investigations revealed high serum uric acid levels (9.36 mg/dL) and a confirmed diagnosis of gouty tophus was made. It is important that pathologist should be aware of the cytological features of gouty tophus, particularly in the case with unusual presentation. Gouty nodulosis has never been reported in literature at this site and we are first to report gouty tophus at this unique site.

Aspiration cytopathology of tophaceous gout: a report of 22 patients

INTRODUCTION

Gout may manifest with crystal-induced arthropathy and/or soft tissue tophi. Demonstration of monosodium urate (MSU) crystals is necessary to establish the diagnosis. Despite the fact that alcohol is an ideal fixative to preserve MSU crystals, very few fine-needle aspiration (FNA) cases of gout have been published.

MATERIALS AND METHODS

A retrospective review was performed for FNA cases diagnosed as tophaceous gout. Samples included unstained smears or smears stained with Diff-Quik or Papanicolaou stain, and formalin-fixed paraffin-embedded cell block stained with hematoxylin and eosin (H&E).

RESULTS

We identified 22 FNA cases involving 18 men and 4 women. Only 7 patients had a clinical history of gout and 5 were taking gout medication. At least 4 patients presented with a clinical diagnosis of rule out sarcoma. All had soft tissue masses from either upper (n = 5) or lower (n = 17) extremities. Extracellular polarizing needle-shaped crystals with negative birefringence were present and visible on unstained, Diff-Quik, or Papanicolaou-stained conventional smears as well as in H&E-stained cell blocks in all cases.

CONCLUSIONS

Our study demonstrates that MSU crystals are readily detectable under polarization on direct smears with or without staining. FNA cytology can serve as an alternative to core needle biopsy or synovial biopsy in not only confirming a diagnosis of tophaceous gout, but also in eliminating a diagnosis of soft tissue sarcoma in those patients where clinical and/or radiologic features were concerning for malignancy.