Adenocarcinoma of Prostate with Small Cell Differentiation Presenting As Refractory Hypokalemia

Authors' Affiliations

Authors: Ammar Alhabhbeh, MD1, Purva Sharma MD2; Mohammad Ali Khan MD3, Koyamangalath Krishnan MD2, Devapiran Jaishankar MD2 Affiliation: 1 Division of Internal Medicine, Quillen College of Medicine, East Tennessee State University 2 Division of Oncology-Hematology, Quillen College of Medicine, East Tennessee State University; 3 Division of Pathology, East Tennessee State University

Faculty Sponsor’s Department

Internal Medicine

Name of Project's Faculty Sponsor

Dr. Devapiran Jaishanker

Classification of First Author

Medical Resident or Clinical Fellow

Type

Poster: Competitive

Project's Category

Reproductive System

Abstract or Artist's Statement

Prostate cancer is among the most common malignancies in males in the United States and adenocarcinoma accounts for 95% of all malignancies of prostate. Rarely prostate cancer can also present as small cell carcinoma. Pure small cell carcinoma is rare at time of initial diagnosis (<2%) however neuroendocrine differentiation into small cell carcinoma may emerge in men who have had previous treatment with ADT for prostate adenocarcinoma. These tumors, sometimes called treatment-related neuroendocrine prostate cancers or aggressive-variant prostate cancers, are increasingly recognized in the castration-resistant phases of disease progression. They account for less than 1% of all prostate cancers. A 73-year-old otherwise male had routine health screening in May 2018. Prostate specific antigen (PSA) level was elevated at 9.53 ng/mL. He had not had a screening PSA for at least two prior years but this was a significant change from prior levels. Patient was asymptomatic however the abnormal laboratory evaluation prompted consultation with Urology. Biopsy of prostate gland confirmed prostatic adenocarcinoma with Gleason's score of 5+ 4 = 9 with bilateral gland involvement. Imaging studies including CT scan of abdomen and pelvis, a bone scan and a PET scan showed no clear evidence of metastatic disease. Patient's clinical stage was determined to be IIIC with T2c N0 M0 disease. Patient began treatment with androgen deprivation therapy and received definitive radiation treatment with external bean radiation therapy from July to September 2018. PSA was 0.08 ng/ml at the end of radiation treatment. Patient did well for about 15 months, after which he had multiple hospital admissions for dyspnea, fluid retention and lower extremity edema. He was also found to have refractory hypokalemia. Patient underwent MRI brain which revealed numerous small enhancing calvarial and skull base lesions consistent with bony metastasis in the skull. Patient also underwent PET/CT scan which showed numerous thoracic spine bony lesions, numerous to count bony metastasis throughout the lumbar spine and pelvis, as well as multiple hepatic lesions. Patient underwent biopsy of right hepatic lobe lesion and pathology was consistent with small cell carcinoma with positive neuroendocrine markers including CD56, synaptophysin and TTF-1. Interestingly patient’s PSA was only 0.09ng/dL. Given refractory hypokalemia, paraneoplastic syndrome was suspected and further work-up was initiated. Serum cortisol levels were elevated at 119.6 mcg/dL (3.7-19.4) and ACTH level was 333 pg/mL (7.2 - 63.3). Aldosterone level was <1 ng/dL (0 - 30.0). Patient was diagnosed with paraneoplastic Cushing syndrome. Given aggressive nature of this small cell transformation, patient was started on treatment with systemic chemotherapy with Carboplatin/Etoposide during the hospital stay, with stabilization of potassium levels. Prostate small cell carcinoma poses a challenge for diagnosis and treatment. In contrast to adenocarcinoma of the prostate, serum prostate-specific antigen (PSA) is not predictive of disease severity, nor is it a useful tumor marker for monitoring progression or surveillance. Patients with prostate small cell cancer presents with more diverse symptoms than any other prostate cancer since it tends to metastasize early. Also paraneoplastic syndromes are more common in prostate small cell cancers as well.

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Adenocarcinoma of Prostate with Small Cell Differentiation Presenting As Refractory Hypokalemia

Prostate cancer is among the most common malignancies in males in the United States and adenocarcinoma accounts for 95% of all malignancies of prostate. Rarely prostate cancer can also present as small cell carcinoma. Pure small cell carcinoma is rare at time of initial diagnosis (<2%) however neuroendocrine differentiation into small cell carcinoma may emerge in men who have had previous treatment with ADT for prostate adenocarcinoma. These tumors, sometimes called treatment-related neuroendocrine prostate cancers or aggressive-variant prostate cancers, are increasingly recognized in the castration-resistant phases of disease progression. They account for less than 1% of all prostate cancers. A 73-year-old otherwise male had routine health screening in May 2018. Prostate specific antigen (PSA) level was elevated at 9.53 ng/mL. He had not had a screening PSA for at least two prior years but this was a significant change from prior levels. Patient was asymptomatic however the abnormal laboratory evaluation prompted consultation with Urology. Biopsy of prostate gland confirmed prostatic adenocarcinoma with Gleason's score of 5+ 4 = 9 with bilateral gland involvement. Imaging studies including CT scan of abdomen and pelvis, a bone scan and a PET scan showed no clear evidence of metastatic disease. Patient's clinical stage was determined to be IIIC with T2c N0 M0 disease. Patient began treatment with androgen deprivation therapy and received definitive radiation treatment with external bean radiation therapy from July to September 2018. PSA was 0.08 ng/ml at the end of radiation treatment. Patient did well for about 15 months, after which he had multiple hospital admissions for dyspnea, fluid retention and lower extremity edema. He was also found to have refractory hypokalemia. Patient underwent MRI brain which revealed numerous small enhancing calvarial and skull base lesions consistent with bony metastasis in the skull. Patient also underwent PET/CT scan which showed numerous thoracic spine bony lesions, numerous to count bony metastasis throughout the lumbar spine and pelvis, as well as multiple hepatic lesions. Patient underwent biopsy of right hepatic lobe lesion and pathology was consistent with small cell carcinoma with positive neuroendocrine markers including CD56, synaptophysin and TTF-1. Interestingly patient’s PSA was only 0.09ng/dL. Given refractory hypokalemia, paraneoplastic syndrome was suspected and further work-up was initiated. Serum cortisol levels were elevated at 119.6 mcg/dL (3.7-19.4) and ACTH level was 333 pg/mL (7.2 - 63.3). Aldosterone level was <1 ng/dL (0 - 30.0). Patient was diagnosed with paraneoplastic Cushing syndrome. Given aggressive nature of this small cell transformation, patient was started on treatment with systemic chemotherapy with Carboplatin/Etoposide during the hospital stay, with stabilization of potassium levels. Prostate small cell carcinoma poses a challenge for diagnosis and treatment. In contrast to adenocarcinoma of the prostate, serum prostate-specific antigen (PSA) is not predictive of disease severity, nor is it a useful tumor marker for monitoring progression or surveillance. Patients with prostate small cell cancer presents with more diverse symptoms than any other prostate cancer since it tends to metastasize early. Also paraneoplastic syndromes are more common in prostate small cell cancers as well.