FLEAS AND TICKS

A CASE OF SIMULTANEOUS DIAGNOSIS OF PAPILLARY THYROID CANCER AND SYSTEMIC MASTOCYTOSIS

Abstract

BACKGROUND
There is no known association between systemic mastocytosis and thyroid cancer. Here, we report a woman diagnosed with papillary thyroid cancer (PTC) and systemic mastocytosis, simultaneously.

CASE
A 43-year-old female presented with cervical lymphadeno- pathy for 3 weeks. She denied any fever, night sweats, flushing, or skin rash. CT scan showed bilateral enlarged cervical lymph nodes with bilateral thyroid nodules. Imaging also revealed multiple lytic lesions in her spine and pelvis. On physical examination, she had palpable cervical lymph nodes with a hard left-sided thyroid nodule. Neck ultrasound revealed a 2.1 cm left hypoechoic thyroid nodule with microcalcifications and cervical lymph nodes. Fine needle aspiration of the thyroid nodule and lymph nodes confirmed PTC. The patient underwent total thyroidectomy with neck dissection, histology confirmed classic PTC (pT3N1bM0). Postsurgical serum thyroglobulin was 17.0 ng/mL and I131 scan showed no metabolic activity in the axial skeleton. Subsequent bone marrow biopsy of the pelvic lytic lesions revealed systemic mastocytosis. The patient was treated with intravenous 4 mg zoledronic acid every 3 months with improvement.

PTC is an indolent malignancy with an excellent 10-year survival rate with rare bone metastases (<4%). Systemic mastocytosis is a proliferation of mast cells that has a wide clinical spectrum from indolent disease to mast cell leukemia. The axial skeleton is affected in up to 50-70% of patients. The most common malignancies known to be associated with systemic mastocytosis are melanoma and non-melanoma skin cancers.

In our patient, initial findings of multiple lytic lesions raised concern for thyroid cancer metastasizing to the bones. However, there was no functional radiographic evidence of metastases. correct diagnosis of concurrent systemic mastocytosis required bone biopsy. Our patient is currently doing well with a good prognosis for both conditions.

CONCLUSION
This is the first known case report of a patient being simultaneously diagnosed with PTC and systemic mastocytosis.