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Year : 2015  |  Volume : 58  |  Issue : 3  |  Page : 404-405
Vibrant colors of uric acid crystals on polarization

Department of Pathology, T. N. Medical College and B. Y. L. Nair Charitable Hospital, Mumbai, Maharashtra, India

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Date of Web Publication14-Aug-2015

How to cite this article:
Jashnani KD, Shetty JB, Desai HM. Vibrant colors of uric acid crystals on polarization. Indian J Pathol Microbiol 2015;58:404-5

How to cite this URL:
Jashnani KD, Shetty JB, Desai HM. Vibrant colors of uric acid crystals on polarization. Indian J Pathol Microbiol [serial online] 2015 [cited 2022 Jan 22];58:404-5. Available from: https://www.ijpmonline.org/text.asp?2015/58/3/404/162935

A 70-year-old male came to the cytology OPD with complaints of a swelling on the dorsum of left foot just below the fourth and fifth toe. The swelling measured approximately 2.5 cm × 2 cm, was firm in consistency, non-mobile and nontender. Radiograph of the feet showed soft tissue swelling overlying the base of fourth and fifth toe. There was no evidence of calcification or lucency seen within the swelling. Underlying bone and articular surfaces did not reveal any abnormality. His biochemical investigations done recently revealed normal serum uric acid levels. The patient however was a diabetic on medication. Clinically no diagnosis was made.

Fine needle aspiration cytology was done using a 23 gauge needle. The smear yielded a whitish amorphous material. Two smears were made from the aspirate. One smear was fixed and stained with Papanicolaou stain and the other aspirate was air dried and stained with May Grunwald Giemsa stain.

Microscopy revealed scattered intact and degenerated polymorphs on a background of abundant amorphous granular material. Since the patient was diabetic, we screened the smear extensively for fungal elements which we couldn't find. Instead, we found slender needle-shaped crystals in stacks and dispersed singly. These crystals were seen in air dried Giemsa smear and not in the alcohol fixed papanicolaou stained smear. Polarizing microscopy of the stained smear showed needle shaped birefringent crystals consistent with monosodium urate crystals of gout [Figure 1]. On further diligent search we found the classical tophus showing a central core surrounded by radiating needle-shaped birefringent crystals [Figure 2] and [Figure 3].
Figure 1: Photomicrograph showing birefringent needle-shaped crystals in singles and small stacks on polarization (Giemsa stain, ×400)

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Figure 2: Photomicrograph showing a gouty tophus on polarization (Giemsa stain, ×400)

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Figure 3: Photomicrograph showing higher magnification of the gouty tophus on polarization (Giemsa stain, ×1000)

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Periarticular nodules pose a diagnostic challenge to both clinicians and pathologist. [1] Though gouty tophi presenting as periarticular masses are uncommon, it must be included in the differential diagnosis. The other differentials being rheumatoid nodules, ganglion cysts, pigmented villonodular synovitis, synovial chondromatosis and synovial sarcoma. [1],[2] Diagnosis of gout can be difficult especially when presentation is atypical and serum uric acid levels are normal. [1],[3] In the present case, the patient's recent serum uric acid levels were within the normal range and he did not have any clinical or radiological evidence of arthropathy. He was a diabetic on medication and uric acid levels may be low or normal in diabetics due to the uricosuric action of increased blood glucose level. [1] Lower levels of uric acid are also seen in alcoholics. Paucity of crystalline material with an intense inflammatory reaction may mask the true nature of the lesion. Aspiration of amorphous or granular material in periarticular nodules should alert the cytopathologist to search for characteristic crystals especially in MGG stained smear to avoid a diagnostic pitfall. [2],[4],[5] Birefringent crystals are also found in pseudogout (calcium pyrophosphate). The crystals of gout are needle-shaped with pointed ends and are strongly birefringent whereas the crystals of pseudogout are shorter, rhomboid with blunted ends and display weak birefringence on polarization. [1],[2],[3]

Fine needle aspiration cytology is a simple, minimally invasive and cost-effective tool in explaining the nature of periarticular nodules. [2],[5] In gouty tophus, it has the added advantage of preserving the crystals, hence being more accurate and serves a good replacement to excision or synovial biopsy wherein the urate crystals are often lost during histological processing as they dissolve in formalin. [1],[5]

The cytopathologist must be aware of the morphology of the crystals and the gouty tophus. This will avoid an erroneous diagnosis and also eliminate the need for the patient to undergo further unnecessary investigations. This being a medically treatable condition (anti-uric acid drugs), surgical excision can be avoided.

   References Top

Agarwal K, Puhaja S, Agarwal C, Harbhanjkar A. Fine needle aspiration cytology of gouty tophy with review of literature. J Cytol 2007;24:142-5.  Back to cited text no. 1
  Medknow Journal  
Gupta A, Rai S, Sinha R, Achar C. Tophi as an initial manifestation of gout. J Cytol 2009;26:165-6.  Back to cited text no. 2
[PUBMED]  Medknow Journal  
Bhadani PP, Sah SP, Sen R, Singh RK. Diagnostic value of fine needle aspiration cytology in gouty tophi: A report of 7 cases. Acta Cytol 2006;50:101-4.  Back to cited text no. 3
Tomar R, Srivastava R, Arora VK. Relevance of synovial cells in gouty tophus on fine needle aspiration cytology. Indian J Pathol Microbiol 2014;57:511-2.  Back to cited text no. 4
[PUBMED]  Medknow Journal  
Walke V, Ramraje S, Jadhao V. Cytodiagnosis of gouty tophus. CytoJournal 2013;10:11.  Back to cited text no. 5
[PUBMED]  Medknow Journal  

Correspondence Address:
Dr. Jyothi B Shetty
Department of Pathology, T. N. Medical College and B. Y. L. Nair Charitable Hospital, Dr. A. L. Nair Road, Mumbai Central, Mumbai - 400 008, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.162935

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  [Figure 1], [Figure 2], [Figure 3]


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