Case presentation
A 27 year old man consulted for 2 month history of lower urinary tract symptoms.  On physical exam, he had an enlarged smooth nontender prostate with no nodularities and no blood on examining finger. Traube’s space was obliterated.
Initial workup showed Hb 8.9 g/dL Hct 26.4 % WBC 7.1 x10^9/L (N54% L15% E3% M3% St17% Mye2% Metamyelocytes 6%) Platelets 102 x10^9/L. PT 11.8 sec/ INR 0.98/ PTT 24.5 sec. Crea 1.61 mg/dL (CKD-EPI EGFR 60) BUN 26 mg/dL HCO3 27 meq/L Na 139 mmol/L K 3.4 mmol/L Cl 101 mmol/L iCa 1.16 mg/dL Mg 1.7 mg/dL, TC 170 mg/dL TAG 127 mg/dL HDL 51 mg/dL LDL 110 mg/dL ALT 66 IU AST 62 IU TB 0.56 mg/dL CB 0.17 mg/dL UB 0.39 mg/dL ALP 107 IU/L Albumin 4.47 g/dL. Urinalysis light yellow, clear urine, negative for glucose bile ketones protein nitrites blood and lymphocytes, SG 1.004, pH 7.0, RBC 0/HPF WBC 0/HPF Epithelial cells 0/HPF Casts 0/HPF Bacteria 0/HPF. PSA 0.23 ng/mL was normal for age.
As show in Figure 1, Multiparametric Prostate MRI with contrast showed markedly enlarged prostate gland with intravesical extension measuring 6.6 x 7.1 x 8.7 cm with a volume of 212 ml with a PIRADS 5 score.
FDG PET-CT showed FDG-avid mass in prostate gland, measuring 8.5 x 7.0 x 6.5 cm SUV 9.6, prominent to enlarged bilateral iliac chain lymph nodes, enlarged spleen and multiple osseous lytic and blastic lesions in L1 and L4 vertebral bodies, sacrum and bilateral pelvic bones.
Patient underwent Koelis US-MRI Fusion Transperineal prostate biopsy, bilateral ureteral stenting, with indwelling foley catheter. Histopathology showed round cell malignancy, immunohistochemistry positive for Desmin and myogenin.
As shown in Figure 2, bone marrow showed a markedly hypercellular bone marrow for age (>95%), with extensive infiltration of atypical cells and tumor giant cells. Immunohistochemistry was positive for CD56, Desmin and Myogenin. Genetic tests were positive for PAX3(exon 7):FOXO1(exon 2) fusion gene.
Dynamic Liver CT showed splenomegaly, slightly dilated portal and splenic veins with gastrosplenic collateral vessels and normal-sized liver. Liver elastrography was F0.
Diagnosis was Alveolar Rhabdomyosarcoma of the prostate Stage IVB (cT4N1M1B-bone), with noncirrhotic portal hypertension, postobstructive uropathy s/p Ureteral stenting bilateral. Patient underwent 3 cycles of Vincristine (1.5 mg/m2), Dactinomycin (40 mcg/kg) and Cyclophosphamide (1200 mg/m2) MESNA. He was given Denosumab every 28 days and Caltrate advanced 2 tabs TID for bone protection and Carvedilol 6.25 mg daily for portal hypertension.
On serial follow-up, liver enzymes peaked at ALT 375 IU/L, AST 126 IU/L. Patient was given Legalon 140 mg TID, Transmetil 500 mg OD, Godex DS 300 mg capsule TID, Essentiale forte TID with decrease in liver enzymes. Creatinine trends remained stable ranging from 0.7 to 0.8 mg/dL.
After 3 cycles, repeat FDG PET-CT showed significant regression in size and extent of hypermetabolism in the prostatic mass, with interval increase in hypermetabolic activity in its left prostatic lobe attributed to residual active malignancy. There was interval non-demonstration of the hypermetabolic iliac chain lymph nodes, stable mixed lytic-blastic lesions in the thoraco-lumbar vertebral bodies and sacrum.