This document describes a case of a 72-year-old man who presented with breathlessness, cough, and recently developed easy fatigability and drooping of the left eye. Imaging showed a mediastinal mass. He was diagnosed with thymoma and myasthenia gravis. He underwent surgery to remove the mass. Histopathological examination found it to be a thymic marginal zone lymphoma. Immunohistochemistry supported this diagnosis. The surgery achieved a complete excision and the patient's myasthenia gravis symptoms improved with medication. He has been followed up for 3 months since with no recurrence.

1. Thymic Marginal zone lymphoma
presenting with Myasthenia Gravis
Shruthi KP*, Indu R Nair**, Balasubramoniam K R***,
Pavithran K*.
Departments of Medical Oncology*, Pathology** and
cardiovascular and Thoracic surgery***,
Amrita Institute of medical Sciences,
Amrita University, Kochi-682041, India

2. Introduction
Extranodal marginal zone B-cell lymphoma of
mucosa associated lymphoid tissue (MALT) arising from
the thymus is a rare disease. 43 cases have been
described in the English literature. 27 patients were
Asian. Compared to MALT lymphomas occurring in other
organs, thymic MALT lymphomas demonstrate several
distinctive clinicopathological and molecular features
such as frequent cyst formation, consistent plasma cell
differentiation with predominantly IgA expression and
secretion, and lack MALT lymphoma specific
translocations. We describe the clinicopatholgic and IHC
characteristics of a case of MALT lymphomas arising from
the thymus which presented with myesthenia gravis.

3. History
• A 72 yr old male
• Breathlessness and cough of 3 years.
• Recent onset easy fatigability and drooping of left eye.
• No fever or weight loss.
• He consulted a local hospital
• Physical examination : conscious, oriented SPO2 - 97%
RA PR - 80/mt ,BP - 130/100 ,No lymphadenopathy
• CVS - S1 S2+,bilateral wheeze .Ptosis of the left eye +
• Chest x ray was taken which showed mediastinal
widening.

4. CT Scan
• CT scan chest showed a 4.8 x 4.4x 5.2 cm well
defined lesion with smooth margins with superior
and posterior mediastinum, in retro tracheal and
left para esophageal location.
• Lesion cause anterior and right lateral
displacement of trachea, abutting arch of aorta
and major neck vessels.
• The radiological differential diagnosis was
bronchogenic cyst with hyperintense contents or
mediastinal tumour.

5. • Clinical diagnosis was thymoma with myasthenia
gravis.
• Complete blood count, renal and liver functions
were normal.
• Electrophysiological study showed evidence for
postsynaptic neuromuscular junction
dysfunction.
• Acetylcholine Receptor Antibody was positive in
the serum.
• EBUS-FNAC : suspicious malignant cells seen in
cell block

6. Surgery
• He underwent VATS mediastinal tumour
excision.
• Findings :6 x 4 cm firm mass overlying SVC -
RA junction. No pleural effusion/metastatic
deposits . Normal lung parenchyma
• The mass was excised completely.
• Histopathology showed a poorly differentiated
neoplasm. Immunohistochemistry was
performed .

7. H&E X 40
H&E x100
H&Ex400

8. CD 20 Bcl 2
CD 23 Ki 67

9. DIAGNOSIS
• On IHC - cells were positive for LCA, CD20,
BCL2 and negative for CK, p63, CD3, BCL6,
CD10, CD5, CD23 and Tdt.
• Ki 67 is less than 10%.
• CD23 showed expanded and disrupted FDC
meshwork in many of the nodules.
• Findings are of Thymic marginal zone
lymphoma

10. Follow up
• As the excision was complete, he was kept
under follow up.
• Mysthenia improved with pyridostigmine and
neostigmine.
• He is doing well and is on regular follow up for
past 3 months