A 66 year old woman with history of iron deficiency anemia, tuberculosis (TB), pulmonary mycobacterium avium complex (MAC) and thymoma presented to the ED for symptomatic anemia. She was well until 6 months prior to admission when she presented with persistent fever and cough, and was diagnosed with TB. She was treated with RIPE therapy with good response. Three months later, she was admitted with recurrent symptoms and found to have pulmonary MAC. Azithromycin was added to her RIPE regimen with resolution of symptoms. A thymoma was found incidentally and thymectomy revealed a 6 cm corticomedullary thymoma with clean margins.
On routine labs three weeks later, her hemoglobin dropped from 9 g/L to 5 g/L, prompting referral to the ED. Vital signs were unremarkable and physical exam notable for a pale thin woman with well-healed surgical scar on her chest. Labs revealed WBC 4, 800/μL, MCV 97.4, and platelets 244 K/μL. Anemia workup showed elevated iron of 176 μg/mL, iron saturation 94%, ferritin 921.1 ng/mL, and reticulocyte index of 0.1. Vitamin B12, folate, and TSH levels were normal. Hemolysis labs and viral testing were negative. Bone marrow biopsy showed nearly absent erythropoiesis with other cell lines preserved, and no evidence of malignancy. SPEP showed no M spike but was significant for hypogammaglobulinemia with IgG 470 mg/dL and IgM 9 mg/dL. B- and T-cell lymphocyte subsets showed slightly low NK and CD45 T cells. She was diagnosed with pure red cell aplasia (PRCA) and hypogammaglobulinemia secondary to thymoma. She was treated with supportive transfusion and prednisone, later switched to cyclosporine, for management of PRCA. She was started on intermittent IVIG for the treatment of hypogammaglobulinemia.
Thymomas are rare anterior mediastinal neoplasms with an incidence of 0.15 per 100,000 person-years in the U.S. They are often found incidentally or present with paraneoplastic syndromes, the most common of which is myasthenia gravis. Less common syndromes include PRCA and Good syndrome. These syndromes can present before or after thymoma diagnosis and often do not resolve with thymectomy.
PRCA occurs in 5-15% of patients and is characterized by the absence of erythroid precursors. The mainstay of treatment is thymectomy, immunosuppressants, and supportive transfusion. Mean survival is 12 years with the most common cause of morbidity and mortality being infection related to immunosuppressants.
Combined humoral and cellular immunodeficiency in the setting of thymoma is known as Good syndrome and develops in 3-6% of patients. It is often characterized by hypogammaglobulinemia, low B cells, variable defects in cell-mediated immunity with a CD4 lymphopenia, an inverted CD4+/CD8+ T cell ratio and reduced T cell mitogen proliferative responses. These patients are prone to recurrent infections of the upper and lower respiratory tract and often have poor prognoses as they tend to present with severe viral and fungal opportunistic infections. Intravenous immunoglobulin (IVIG) therapy reduces the incidence of infections and the frequency of hospitalizations.
This case highlights two rare thymoma-related paraneoplastic disorders, one of which presented prior to diagnosis and the other after thymectomy. Patients with history of thymoma should receive routine screening for anemia. Those who develop opportunistic or recurrent infections should undergo immunodeficiency evaluation as early detection can lead to preventive treatment and improved mortality.
To cite this abstract:Runcie KD, Gee EY. A “Good” Case of Thymoma. Abstract published at Hospital Medicine 2016, March 6-9, San Diego, Calif. Abstract 769. Journal of Hospital Medicine. 2016; 11 (suppl 1). https://www.shmabstracts.com/abstract/a-good-case-of-thymoma/. Accessed May 22, 2019.