HIV-related primary mediastinal large B-cell lymphoma with multisystemic involvement
Presentation
Presented with acute renal failure and ballotable kidneys.
Patient Data
Large anterosuperior mediastinal mass with central necrosis, encasing and compressing the left pulmonary arteries and left bronchi resulting in segmental lung collapse. The superior vena cava is compressed between the mass and the enlarged right paratracheal node. Filling defect within the left brachiocephalic vein suggestive of thrombus.
Multiple scattered bilateral lung nodules with bilateral mild pleural effusions, more on the left.
Enlarged, matted lymphadenopathy at the porta hepatis (encasing the hepatic inferior vena cava) and paraaortic regions. Grossly enlarged kidneys with confluent hypodense masses replacing the normal renal parenchyma suggestive of diffuse infiltration. The left renal pelvis is compressed with calyceal dilatation. Bilateral small adrenal nodules. Bilateral ovarian masses with central necrosis were also seen. Uterus is not enlarged. Moderate ascites.
No suspicious bony lesion.
Ultrasound guided core biopsy of the large anterior mediastinal mass was performed.
Histopathology
Macroscopic description: Specimen consists of 3 cores of whitish tissue measuring 12mm to 14mm in length. All submitted in 1 block.
Microscopic description: Levels show 3 strips of fibro collagenous tissue, all diffusely infiltrated by medium to large sized malignant lymphoid cells with accompanying compartmentalizing fibrosis and interspersed small mature lymphocytes. The cells exhibit round to oval nuclei with irregular nuclear membrane, one of more visible nucleoli with scanty to moderate clear cytoplasm. Occasional small lymphocytes and eosinophils are noted in the background. Mitoses are easily seen. No Reed-Sternberg cells or granuloma.
The malignant cells are diffusely positive for CD20 and PAX5. They are positive for bcl-2, bcl-6, MUM-1 and weakly positive for CD30 (mainly background staining pattern). They are negative for CD3, CD5, CD10, CD117 and pancytokeratin. Ki 67 proliferative index is >85%.
Diagnosis: Primary mediastinal large B-cell lymphoma (PMLBCL)
Case Discussion
Due to the findings of a large mediastinal mass with widespread disease involving multiple organs (lungs, bilateral kidneys, both ovaries and bilateral adrenal glands) as well as involving nodal groups above and below the diaphragm, lymphoma is the most likely diagnosis.
This patient was subsequently diagnosed to be HIV-positive, therefore this could represent a case of HIV-related primary mediastinal large B-cell lymphoma (PMLBCL) with aggressive multisystem involvement. Although the most common non-Hodgkin's lymphoma types seen in HIV patients are diffuse large B-cell lymphoma, Burkitt lymphoma and primary CNS lymphoma, several cases of PMLBCL in HIV patients have been reported 1-3.