Cytologically Yours: CoW: 20140220

Clinical Summary

The patient is a 58 year old male with back and neck pain.

Past Medical History

• Cervical spondylosis
• Hypertension
• Hyperlipidemia

Past Surgical History

• No surgical history

Radiology

• Ultrasound of the neck shows a solid interpolar nodule 1.8 x 1.6 cm in the left lobe of the thyroid.

Clinical Plan

Fine needle aspiration of the nodule is scheduled.

Pathology

Cytology

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  40x magnification of highly atypical malignant appearing cells.

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  20x magnification showing osteoid formation.

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  40x magnification showing osteoid formation and malignant appearing cells.

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  40x magnification showing osteoid formation and malignant appearing cells.

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  40x magnification of osteoid.

Resident Questions

• What is the differential diagnosis?

In a cellular thyroid lesion, follicular neoplasm, including adenoma and carcinoma, and cellular benign follicular nodule are in the differential. Also in the differential is the follicular variant of papillary carcinoma.   

• What are the molecular features that differentiate follicular carcinoma and papillary carcinoma?

"> Follicular carcinoma show PAX8-PPAR gamma translocations and papillary carcinoma shows BRAF mutations and RET/PTC rearrangements.

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Final Diagnosis

Cytology

• Follicular neoplasm.

Discussion

The diagnostic criteria for follicular lesions are based on cellularity and the presence of colloid. Follicular lesions will be cellular with an absence of the variability in the size of the follicular groups, with a predominately microfollicular pattern. Colloid will be scant to absent, except for the presence of inspissated colloid in the center of follicular groups. There is often a disorganized, crowded follicular pattern with some nucleomegaly and nucleoli.