Journal of Cancer Research and Therapeutics Medknow Publications on behalf of the Association of Radiation Oncologists of India (AROI) ISSN: 0973-1482 EISSN: 1998-4138 Vol. 3, Num. 1, 2007, pp. 43-46

Journal of Cancer Research and Therapeutics, Vol. 3, No. 1, January-March, 2007, pp. 43-46

Brief Communications

Myelodysplastic syndrome and pancytopenia responding to treatment of hyperthyroidism: Peripheral blood and bone marrow analysis before and after antihormonal treatment

Akoum Riad, Michel Saade, Wafic Tabbara, Emile Brihi, Marwan Masri, Khaled Habib, Gerard Abadjian

Department of Oncology, Rizk Hospital, Beirut
Correspondence Address:PO Box 11-3288, Rizk Hospital, Beirut,rakoum@yahoo.com

Code Number: cn07011

Abstract

Keywords: Hyperthyroidism, myelodysplastic syndrome, pancytopenia, reversible

Introduction

The myelodysplastic syndrome is a clonal hemopoietic disorder characterized by an abnormal marrow proliferation that merges into acute myelogenous leukemia. It may be associated with prior cytotoxic treatment and recognized as a late complication of chemotherapy particularly with alkylating agent (t-MDS). It may also be secondary to vitamin deficiency or acute toxicity and then it is often reversible.[1],[2]

In the myelodysplastic syndrome, anemia is present in over 85% of patients with increased mean corpuscular volume (MCV), neutropenia is present in about 50% of the patients with frequently increased monocytosis, thrombocytopenia is present in 25% of the patients, the marrow cellularity is usually normal or increased, the proerythroblasts may be in excess with pathologic sideroblasts, a granulocytic hyperplasia is frequent, megakaryocytes are present and an increase in reticulin and collagen fibers of varying degree is common.

Untreated hyperthyroidism can be associated with anemia (34%), leucocytopenia (5.8%) and thrombocytopenia (3.3%).[1],[2],[3] The mechanisms invoked for these single lineage abnormalities were related to the decreased circulating time for some and to the autoimmune reaction for others. Pancytopenia has been rarely reported. All cases were totally reversible as the antithyroid hormonal treatment proceeded. The presence of a myelodysplastic syndrome has not yet been clearly described as a possible consequence of hyperthyroidism.

The observation of a new case of pancytopenia revealing a myelodysplastic syndrome in a patient with hyperthyroidism, which completely resolved under medical treatment led us to review the literature. In gathering information for this article, we systematically searched Pub Med for articles published from 1962 to august 2004.

Case report

A 65-year-old-woman presented in October 2003 with more than a 10 weeks' history of weakness, nervousness, back pain, weight loss of 20 kg, palpitations, pallor, low grade fever (38° - 38.5°C), fine tremor and excessive perspiration. She had no evidence of focal or general infection. She was noted to have an enlarged neck with a very large multinodular goiter. Complete work-up including isotopic bone scan, lumbar and dorsal CT scan and routine X-rays showed only severe osteopenia. CT scan of the neck, the thorax and the abdomen showed a huge multinodular goiter extending into the retrosternal area. The electrocardiogram showed a supraventricular tachyarrythmia. Thyroid function tests revealed a TSH level of 0.02 mIU/l (N: 0.25-4) and an fT3 level of 18 pmol/l (N: 4-10). The diagnosis of toxic multinodular goiter was made.

A blood count at diagnosis showed the white blood cells at 2500 /ul and the platelets at 58.000/ul. The hemoglobin level was 6.5 g/dl, the MCV was 88 fl. The sedimentation rate ESR was 115 mm/h.

To explain the pancytopenia, a bone marrow aspiration and biopsy were performed: a moderately hypercellular marrow with moderate myelofibrosis and arrested hematopoiesis was noted.

The patient was started on an antithyroid agent, carbimazole: 30 mg tid. A marked improvement in the clinical picture was seen within one month and the thyroid function returned to normal. The peripheral blood counts became normal one month later and the bone marrow analysis performed four months later showed normal hematopoiesis with no evidence of myelodysplasia [Figure - 1],[Figure - 2]. A persistent response was observed six months later under medical treatment. The patient refused surgical treatment.

Discussion

The fortuitous detection of a pancytopenic myelodysplasia in this 65-year-old lady with thyrotoxicosis led us to consider these two coexisting diseases as two separate entities that are not uncommon at this age group. The unexpected normalization of the hematological disorders under only anti-thyroid hormonal treatment is an uncommon event since the natural history of almost all primary myelodysplastic syndromes is to progress into acute myelogenous leukemia.[1],[2]

Because of the unavailability of a cytogenetic laboratory, no further karyotypic analysis was performed in this case to look for 5q and/or 7q deletion seen in approximately 80% of toxic myelodysplastic syndromes and toxic acute myelogenous leukemias (t-MDS / t-AML). The patient denied ingesting any toxic drugs and she never received any cytotoxic chemotherapy or radiotherapy.

The reversible myelodysplastic syndrome has been described[4] separately from the hematological picture of hyperthyroidism. Reversible pancytopenia has been described after successful treatment of hyperthyroidism [Table - 1].[5],[6],[9],[10],[11],[12] Thyroid hormones have been known to potentiate erythropoiesis via the β-adrenergic receptors and reduce the life-span of whole blood component.[5] Immunological mechanisms have also been suggested to be involved in the reduction of the life-span of blood cells and platelets.[5]

The toxicity of thyroid hormones on bone marrow stem cells may be direct or mediated by proteic inhibitory or growth factors. Although the ESR was accelerated suggesting an inflammatory process, all the routine immunologic tests were negative and after normalization of the blood picture it remains accelerated at> 60 mm/h.

Shaw and Mehta[6] suggest that thyroid hormones may have a direct effect on hematopoiesis at a stage earlier than erythropoietic stem cell differentiation, disturbing maturation and differentiation of the pluripotent stem cells. Granulopoiesis abnormalities and leukemia have also been described in association with hyperthyroidism and attributed to the direct toxicity of the thyroid hormones.[7],[8] In conclusion: Reversible myelodysplastic syndrome may be part of the blood picture changes seen in hyperthyroidism, probably due to direct toxic mechanism.

References

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