Colloid and pigmented histiocytes in lymph node aspirates as a clue to metastasis in patients with a history of papillary thyroid carcinoma.

Colloid material and pigmented histiocytes, and to lesser degree calcification and multinucleated giant cells, when seen in an aspirate without tumor cells, raises suspicion metastatic disease. On the contrary, the lymphoid fragments can be regarded as supportive evidence of adequate sampling and a true negative result.