Endocrine Abstracts

A 24-year-old woman presented with stridor resulting from a large, firm, anterior neck mass. At age six she had been treated for acute lymphoblastic leukaemia (ALL) with vincristine, prednisolone, daunorubicin, asparaginase, prophylactic cranial radiotherapy and intrathecal methotrexate. She also had primary hypothyroidism with strongly positive thyroid peroxidase antibodies.

The mass had been gradually enlarging for 6 months, causing exertional breathlessness. For 3 days prior to admission, she described severe nocturnal dyspnoea and stridor. She also noted 3 months of weight loss (1 stone) and drenching night sweats. After a single 8 mg i.v. dexamethasone dose the mass significantly reduced in size and the stridor resolved.

CT showed a large mass intrinsic to the gland measuring 5.6×7.4×6.3 cm. Abnormal tissue compressed and invaded the trachea. There was multi-level lymphadenopathy. Open biopsy revealed histiocytic sarcoma of the thyroid.

There was minimal response to CHOP chemotherapy but radiotherapy gave significant shrinkage. As ultrasound showed residual disease a thyroidectomy was performed. Histology confirmed radiotherapy changes, a follicular adenoma and residual histiocytic sarcoma with clear margins. Ultrasound at three months showed no evidence of recurrence.

Histiocytic sarcomas are rare. Found most commonly in the skin, lymph nodes and gastrointestinal tract, there are no documented cases in the thyroid. There are reports of histiocytic sarcoma following ALL, however all cases occurred within two years of the leukaemia. It has been suggested these may be related to the use of alkylating agents. There are historical reports of histiocytic malignancies associated with raised thyroid antibodies, but these predate modern immunohistochemical staining and WHO’s recategorisation of lymphomas in 1997. The majority of these previously reported ‘histiocytic lymphomas’ are now thought to reflect alternative diagnoses.

We present the first reported case of histiocytic sarcoma of the thyroid. The patient appears to have been successfully treated with chemotherapy, radiotherapy and surgery.