Thyroid Research and Practice

: 2012  |  Volume : 9  |  Issue : 2  |  Page : 72--74

Asymptomatic intrathyroid "Water Clear Cell" parathyroid adenoma: A rare entity

Harveen K Gulati, Mani Anand, Sanjay D Deshmukh 
 Department of Pathology, Smt. Kashibai Navale Medical College and General Hospital, Narhe, Pune, Maharashtra, India

Correspondence Address:
Harveen K Gulati
Department of Pathology, Smt. Kashibai Navale Medical College and General Hospital, Narhe, Off Pune-Mumbai Bypass, Pune- 411 041, Maharashtra

How to cite this article:
Gulati HK, Anand M, Deshmukh SD. Asymptomatic intrathyroid "Water Clear Cell" parathyroid adenoma: A rare entity.Thyroid Res Pract 2012;9:72-74

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Gulati HK, Anand M, Deshmukh SD. Asymptomatic intrathyroid "Water Clear Cell" parathyroid adenoma: A rare entity. Thyroid Res Pract [serial online] 2012 [cited 2022 Oct 5 ];9:72-74
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A 50-year-old female presented with right-sided neck swelling which was noticed two months back. She had no other significant present or past history. On examination, the patient was afebrile with a pulse rate of 74/ min and a blood pressure of 120/70 mm Hg. Local examination revealed a right-sided neck swelling measuring 5 × 3 × 2 cm which moved on deglutination but not on protrusion of tongue. The swelling was firm in consistency and was freely mobile. Laboratory investigations revealed a normal thyroid function test (T3-1.24 ng/ml; T4-6.59 μg/dl and TSH- 1.20 IU/ml); however, serum calcium level was found to be in high normal range of 10.4 mg/dl. Ultrasonography (USG) was performed which revealed an enlarged thyroid gland with two nodules in the right lobe of thyroid, larger measuring 24 × 15mm and smaller measuring 11 × 10mm respectively. USG-guided fine needle aspiration cytology from the larger nodule was performed which revealed a colloid nodule. With a preoperative diagnosis of colloid nodule in a multinodular goitre, the patient was taken up for right hemithyroidectomy. Both parathyroid glands on the left side and one on the right side were identified intra operatively and were found to be unremarkable grossly. We received the specimen which comprised right lobe of thyroid measuring 5.5 × 3 × 2 cm. Cut surface showed a large mutiloculated colloid filled cyst measuring 2.5 × 1.5 × 1cm. Also seen was a single well circumscribed gray white nodule measuring 1 cm in diameter [Figure 1]. Microscopic examination from the gray white nodule revealed an encapsulated lesion composed of cells arranged in organoid, acinar and pseudoglandular pattern separated by thin fibrovascular septae [Figure 2]a. The cells were large with abundant amount of optically "clear" cytoplasm and a pyknotic nucleus [Figure 2]b. The cells were found to be Periodic Acid Schiff (PAS) positive and diastase resistant [Figure 3]. No other cell types were noted. No atypia, mitoses or capsular/vascular invasion were noted. The surrounding tissue revealed thyroid follicle separated by fibrous bands. The connective tissue stroma showed prominent lymphocytic infiltration which formed nodules with germinal centres at places. No Hόrthle cell change was noted. Section from the colloid nodule showed large colloid filled follicles along with hemosiderin laden macrophages. Immunohistochemical examination was done to rule out other clear cell neoplasms. The cells were found to be positive for chromogranin and negative for CD10, S100 and epithelial membrane antigen (EMA) [Figure 3]. With the above findings and clinical evidence of absence of enlargement of other parathyroid glands, a diagnosis of "water clear cell" parathyroid adenoma (WCCPA) in the setting of lymphocytic thyroiditis and colloid cyst was offered. Post operative serum calcium level was 8.4 mg/dl.{Figure 1}{Figure 2}{Figure 3}

Thyroid gland represents the second most common site of ectopic parathyroid glands after highly descended lower glands. [1] Various parathyroid pathologies including cyst, hyperplasia, adenoma and carcinoma have been reported in intrathyroidal location with the incidence of intrathyroid parathyroid adenoma (IPA) being 1.4-3.2%. [2] IPA is defined as a parathyroid adenoma surrounded by thyroid tissue in such a way that in order to be removed, it requires a thyroidectomy. [1] Adenomas of parathyroid gland usually contain mixed cell population; however, those composed solely of water clear cells are exceptionally rare (with only nine cases reported in literature). [3],[4],[5] Furthermore, to the best of our knowledge, only a single case of WCCPA in intrathyroidal location has been reported in literature so far. [5] The origin of these clear cells is unknown; however, Roth has postulated the origin of clear vacuoles from Golgi apparatus. [6] Their clinical profile is similar to regular adenomas with only two out of nine cases being asymptomatic. [3],[4],[7] The maximum tumor size has been reported to be 6.8 cm with minimum of 1.5 cm. [3],[4],[7] The smaller size in our case can be explained by its early incidental discovery. The adenoma has been found to be of equal distribution between right and left glands. [3],[4],[5],[7] The differential diagnosis includes chief cell adenoma which may have clear cell component but is predominantly formed by glycogen-containing chief cells. These cells are 6-8 μm in diameter with a moderate amount of pale granular cytoplasm as compared to water clear cells which have abundant amount of optically clear cytoplasm. [8] Differentials include clear cell paragangliomas, the sustentacular cells of which are S100 positive. [7] Other clear cell epithelial tumors like renal cell carcinoma which is CD10 positive and clear cell salivary gland neoplasms which are EMA positive should also be included in the differential diagnosis. [7] Negativity of all these stains in association with the clinical and morphologic features clinched the diagnosis of WCCPA within a intrathyroidal location. To conclude, we present an extremely rare case of intrathyroidal WCCPA which was discovered incidentally after thyroid surgery.


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