Discussion
Prostate cancer is the third leading cause of cancer death in
men.4 It is the most common non-cutaneous cancer in
men in the United States.5 It typically affects males
above the age of 50. However, younger age groups have been identified
since using P.S.A. as a screening tool.6 The five-year
survival rate of localized and regional prostate cancer is more than
99%, whereas metastatic prostate cancer is only
30%1. At presentation, about 78% of the lesions are
localized, and only 6% of cases present with
metastasis.1 Spread to other body parts usually occurs
through lymphatic, hematogenous, or direct extension. Bone and lymph
nodes are common sites among those with metastatic lesions, with
pulmonary, hepatic, retroperitoneal, or abdominal metastasis very
uncommon.6 Mediastinal metastasis is exceedingly rare
and can present with mediastinal adenopathy in 0.6% of the
cases.7 Only one other case of prostate cancer is
reported presenting with a mediastinal mass.8 In the
United States, significant racial differences exist in the management of
prostate cancer.9
Management initially begins with screening, either by measuring P.S.A.
once a patient reaches above the age of 50 or performing a digital
rectal examination to check for a palpable
abnormality.6 Confirmatory tests involve performing an
ultrasound-guided transrectal prostate biopsy in a grid-like pattern and
staging it based on Gleason’s scoring.10 Even though
it is the standard of care, it can miss up to 28% of lesions and
undergrade up to 17%.11 Hence, newer diagnostic
tests, biomarkers, and imaging modalities have been developed to improve
diagnosis and risk stratification accuracy.10 One such
biomarker that is specific to primary prostatic adenocarcinoma is
NKX3.1.12,13, coded for by a gene located on
chromosome 8p, which aids prostate development and acts as a tumor
suppressor gene. Loss of this marker correlates with microenvironment
inflammation, usually found in the early stages of prostate
cancer.14
Studies have also shown that NKX3.1 interacts with M.Y.C., and a
reduction in the former results in proliferative effects of M.Y.C.,
leading to cancer progression and relapse.15 It can
also distinguish between high-grade prostate cancer and high-grade
bladder cancer.16 It can be used to identify
metastasis and has shown a sensitivity and specificity of 98.6 and
98.7% respectively in a cohort of metastatic
tumors.17 Studies have also shown that it is more
specific than P.S.A. when identifying prostate
cancer.18 Based on our discussion, our case also has
similar pertinent findings. Our patient was an African American male
aged 68 years with a late diagnosis due to patient non-compliance; a
biopsy of his metastatic mass was positive for NKX3.1. Even though a
digital rectal exam or a prostate-specific antigen due to the absence of
genitourinary symptoms and a different presentation, a diagnosis was
confirmed based on immunohistochemistry. Since his primary symptoms
improved his condition was further managed on an outpatient basis with
the hematology-oncology team.
Author Contributions:
1, Muhammad Haider - Department of Medicine, Richmond University Medical
Center/Mount Sinai
Prepared, reviewed and edited the manuscript
2, Arun Umesh Mahtani- Department of Medicine, Richmond University
Medical Center/Mount Sinai
Reviewed and edited the manuscript/figures
3, Bachar Botrus - Department of Medicine, Richmond University Medical
Center/Mount Sinai
Reviewed and edited the manuscript/figures
4, Foma Munoh Kenne - Department of Hematology/Oncology, Richmond
University Medical Center/Mount Sinai
Reviewed and edited the manuscript
5, Madiha Fatima Master - Philadelphia College Of Osteopathic Medicine
Reviewed and edited the manuscript