Investigations
His initial lab results showed a white blood cell (WBC) count of 3.9
K/uL, hemoglobin of 12.5 gm/dL, a platelet count of 187 K/uL, blood urea
nitrogen (BUN) of 19 mg/dL, and creatinine (Cr) of 1.6 mg/dL. Other
investigations showed an iron level of 57 ug/dl, total iron binding
capacity (TIBC) of 227mcg/L, ferritin of 469.4 ng/dL, a lactate
dehydrogenase of 286 U/L, an E.S.R. of 31mm/hr, a high sensitivity
troponin of 30.8 ng/L, plasma total free metanephrine of 75 pg/mL,
plasma normetanephrine of 236 pg/mL, and total plasma metanephrine of
311 pg/mL.
An electrocardiogram (EKG) was done, which showed normal sinus rhythm.
A chest x-ray (C.X.R.) was also done, which showed a 1.3 cm nodule noted
projecting over the fifth rib anterolaterally and in the right, mid lung
field peripherally, widening of the mediastinum, and sclerotic 1 cm
density in the right, and 1.1 cm density in the left humerus shaft
[figure1].
Following this result, he underwent a computed tomography angiogram
(C.T.A.) of the chest, abdomen, and pelvis (C.A.P.) to rule out aortic
dissection. It showed a large enhancing soft tissue mass in the
posterior mediastinum measuring 5.0 x 4.3 cm [figure 2 and 3]. The
thoracic aorta was unremarkable. There was no pericardial or pleural
effusion. The lungs were clear. There was no thoracic lymphadenopathy,
and extensive retroperitoneal abdominal lymphadenopathy was noted.
Additionally, mild left-sided hydronephrosis and hydroureter were seen
due to lymphadenopathy.
A renal sonogram revealed minimal left kidney hydronephrosis,a pre-void
bladder volume of 135.3 ccs, and prostatomegaly measuring 5.0 x 5.0 x
5.8 cm and weighing 75.6 gms. The right kidney was unremarkable on the
renal sonogram [figure 4].
Given the findings of the C.T.A., interventional radiology (I.R.) was
consulted to biopsy the mass. The biopsy was technically challenging due
to the overlying rib, the adjacent descending thoracic aorta, and
intercostal vessels in the single available window. The needle was
successfully positioned in the posterior border of the mass. No bleeding
was incurred.
The biopsy results favored metastatic prostate carcinoma with positive
immunostaining of NKX3.1 and positive immunohistochemistry of PD-L1 CPS
[Figures 5 and 6].