Management of Advanced Thymoma Presenting with Myasthenia Gravis in a Resource-limited Setting: A Case Report

Abstract

Thymomas are rare tumours which generally account for only 0.2 - 1.5% of mediastinal tumours in adults. Around 40% of patients present with systemic symptoms such as motor weakness due to myasthenia gravis (MG), pure red cell aplasia, and hypogammaglobulinemia. Based on recent guidelines, management of advanced thymoma uses a multimodal approach, which is thymectomy followed by radiotherapy, but not all health care centers have radiotherapy facilities. A 52-year-old woman presented with nasal voice and had difficulty swallowing food. Patient was diagnosed with myasthenia gravis (MG). CT scan with contrast of the thorax showed a heterogenous solid mass in anterior mediastinum. Histopathological examination showed thymoma type B2. Thymectomy followed by seven cycles of platinum-based chemotherapy were done on the patient. Evaluation afterward showed complete remission of thymoma. The patient's motor weakness improved after the chemotherapy. Post-chemotherapy period was uneventful at six months on follow-up visit. The dosage of acetylcholinesterase inhibitor drug is reduced periodically due to improvement in motor weakness. The case emphasizes how to manage an advanced thymoma with MG with limited therapeutic options, and the importance of multidisciplinary management involving oncologists, surgeons, and neurologists.

Keywords: case report; chemotherapy; myasthenia gravis; thymectomy; thymoma.

Figure 1

Chest x-ray showing mediastinal ante-rior mass (yellow arrow).

Figure 2

CT scan showing mediastinal anterior mass (yellow arrows).

Figure 3

Histopathological Examination. (A) Well demarcated, lobulated tumor mass, partially covered by a connective tissue capsule (red arrow) (HE, 40x); (B) Lobulated tumour mass circumscribed by fibrous connective tissue septa (red arrow) (HE400x); (C) Proliferation of lymphoid cells (predominantly mature lymphocytes) was seen with round-oval cell morphology, round-oval nuclei, mild nuclear pleomorphic, with vesicular nuclei in between (HE,400x); (D) Cells appear scattered in a single cell and cell cluster pattern (>3 cells) among mature lymphocytes. Mitoses are hard to find (HE, 400x).

Figure 4

CT scan showing (A)Complete remission after four series of chemotherapy; (B) No recurrence after six months on follow-up.