ONCOCYTIC/HURTHLE CELL CARCINOMA OF THE THYROID

Case provided by Amy Stein, MD

Case History

The patient is an 86 year old woman who noticed a painless lump in her neck seven months prior to admission.  An ultrasound at that time showed an enlarged left thyroid lobe (6 cm compared to the right side which was 4.1 cm) which was diffusely enlarged and heterogeneous with some cystic spaces but without discrete nodules.  A repeat ultrasound was performed five months later which showed that the left lobe had increased to 7.3 cm in size, though it otherwise showed similar characteristics to the prior ultrasound.  A fine needle aspirate of the left thyroid followed by left thyroidectomy was performed.

Microscopic Findings

The fine needle aspirate showed a hypercellular specimen consisting of a predominance of oncocytic/Hurthle cells characterized by cells with abundant granular cytoplasm (stained blue in Papanicolaou stain) in single cells, microfollicles, and sheets with only scant colloid.  The interpretation was suspicious for follicular neoplasm with Hurthle cell change.  The lobectomy specimen showed a Hurthle cell carcinoma consisting of oncocytic/Hurthle cells with abundant pink granular cytoplasm (on Hematoxylin & Eosin stain) with a predominantly solid growth pattern which had foci of capsular and vascular invasion.

Diagnosis

ONCOCYTIC/HURTHLE CELL CARCINOMA

Discussion

Follicular carcinoma is the second most common type of thyroid carcinoma representing approximately 15% of thyroid carcinomas.  Most follicular carcinomas are of the conventional type, with only 20-25% having a Hurthle cell or oncocytic appearance.  The incidence of follicular carcinoma increases with age, particularly in oncocytic/Hurthle cell carcinoma in which the majority are diagnosed in patients over the age of 60.  The risk for follicular carcinoma increases in areas of iodine deficiency and in patients with pre-existing benign thyroid lesions such as benign thyroid nodules, adenomas, and goiter.  Hurthle cell carcinoma consists of tumor cells with abundant granular eosinophilic cytoplasm (oncocytic cells) due to the presence of numerous mitochondria.  All follicular carcinomas require capsular or vascular invasion.  A greater number of oncocytic encapsulated follicular neoplasms qualify as carcinoma based upon capsular or vascular invasion compared to follicular neoplasms with conventional histology.  Approximately 20% of oncocytic neoplasms meet the criteria for a diagnosis of carcinoma.  In the U.S., the 10 year survival for oncocytic carcinoma is 73-76% which is somewhat worse than that for conventional follicular carcinoma which is 83-86%.  This may reflect differences in behavior including lymph node metastases as well as possibly higher recurrence rate and tumor-related mortality.  In addition, poorer outcomes for patients with oncocytic/Hurthle cell carcinoma may reflect their typically older age.  Risk factors which are associated with a greater likelihood of metastasis include tumor size (greater than 4 cm), trabecular or solid growth, mitotic activity, and greater than three foci of angioinvasion.

This patient will be seen several weeks following surgery at a tertiary care center for further treatment recommendations.

 References

  1. Nikiforov, YE.  Diagnostic Pathology and Molecular Genetics of the Thyroid. Philadelphia:  Lippincott Williams & Wilkins, 2009:160-182.
  2. Ghossein, RA, et al.  “Prognostic Factors of Recurrence in Encapsulated Hurthle Cell Carcinoma of the Thyroid Gland:  A Clinicopathologic Study of 50 Cases.  Cancer 2006; 106:  1669-1676.
  3. Stojadinovic, A, et al.  “Hurthle Cell Carcinoma:  A 60-year Experience”.  Annals of Surgical Oncology 2002; 9 (2):  197-203.
  4. Montone, KT, et al.  “The Thyroid Hurthle (Oncocytic) Cell and Its Associated Pathologic Conditions:  A Surgical Pathology and Cytopathology Review”  Archives of Pathology and Laboratory Medicine 2008; 132:  1241-1250.
 SurePath™ Papanicolaou stain; Low Power Magnification: hypercellular specimen
 SurePath™ Papanicolaou stain: Uniform cells with abundant granular cytoplasm in sheets and single cells
 SurePath™ Papanicolaou stain: Uniform cells with abundant granular cytoplasm in sheets and single cells
 SurePath™ Papanicolaou stain; High Power Magnification: Microfollicles and single oncocytic/Hurthle cells with abundant blue-staining granular cytoplasm
SurePath™ Papanicolaou stain; High Power Magnification: Microfollicles and single oncocytic/Hurthle cells with abundant blue-staining granular cytoplasm
SurePath™ Papanicolaou stain; High Power Magnification: Microfollicles and single oncocytic/Hurthle cells with abundant blue-staining granular cytoplasm
H&E Stain; Low Power Magnification: Upper left portion of the thyroid resection slide shows uniform cells with pink staining cytoplasm representing oncocytic/Hurthle cells comprising the tumor. Lower right portion shows the dense eosinophilic capsule
H&E Stain; Low Power Magnification: The neoplasm is composed of oncocytic/Hurthle cells which are uniform with abundant eosinophilic granular cytoplasm
H&E Stain; Low Power Magnification: Dilated vascular space containing invasive oncocytic/Hurthle cell carcinoma
H&E Stain: Carcinoma invading into and filling a vascular channel
H&E: Carcinoma composed of oncocytic/Hurthle cells with abundant eosinophilic cytoplasm invading into a vascular channel within the densely eosinophilic tumor capsule
H&E Stain; High Power Magnification: Resected tumor showing sheets of oncocytic/Hurthle cells which are uniform with abundant eosinophilic granular cytoplasm
H&E Stain; High Power Magnification: Oncocytic/Hurthle cells with round, regular nuclei and abundant eosinophilic granular cytoplasm