An unusual case of pleural nodularity.

A 65-year-old man was referred to the respiratory unit for evaluation of a left lower-zone opacity noted on a chest radiograph. On review, he appeared well and denied any respiratory symptoms. Physical examination was normal. A thoracic computed tomogram (CT) revealed widespread pleural nodularity with fissural and diaphragmatic involvement and prominent mediastinal lymph nodes. An image-guided percutaneous pleural biopsy was arranged. Histological analysis confirmed adenocarcinoma, with initial immunostaining failing to identify the primary site. However, a staging CT scan demonstrated bony lesions and an irregular prostate. Serum PSA level was elevated, and subsequent PSA immunohistochemistry strongly positive; a diagnosis of metastatic prostate cancer was made. Prostate cancer has a well-recognized pattern of metastatic disease (local lymph nodes and bone). Autopsy studies demonstrate that a significant number of patients have pleural involvement, contrasting with the rarity of clinically evident pleural disease during life.

Introduction

Pleural nodularity is commonly noted in patients presenting to the pleural clinic. Unusual causes of malignant pleural disease need to be considered if initial investigations fail to provide a pathological diagnosis.

Case Report

A 65‐year‐old man was referred to the respiratory unit for evaluation of a left lower‐zone, pleural‐based opacity noted on a chest radiograph. The latter had been performed in the local emergency department to which he presented following a mechanical fall. He was an ex‐smoker with a 15‐pack‐year history and had no known occupational exposures. On review, he appeared well and denied any respiratory symptoms. The musculoskeletal chest pain he developed as a result of his fall had improved. Physical examination was normal.

A thoracic computed tomogram (CT) revealed widespread pleural nodularity with fissural and diaphragmatic involvement and prominent mediastinal, pericardial, and right paratracheal lymph nodes (Fig. 1). An image‐guided percutaneous pleural biopsy was arranged for histological confirmation.

Figure 1

Computed tomogram (CT) thorax image demonstrating widespread pleural nodularity.

Histological analysis confirmed adenocarcinoma, with initial immunostaining failing to identify the primary site (Fig. 2). However, a staging CT scan demonstrated early right‐sided hydronephrosis, mixed lytic, and sclerotic bony lesions with an irregular prostate and prominence of the seminal vesicle. A serum PSA level was elevated (293.4 μg/L), and subsequent PSA immunohistochemistry staining on the biopsy sample was strongly positive.

Figure 2

Pleural biopsy showing cells in keeping with adenocarcinoma with strong PSA expression.

He was referred to the Urology Multi‐Disciplinary Team (MDT). Hormone ablation therapy (Degarelix, Ferring Pharmaceuticals Ltd., West Drayton, UK) and chemotherapy were commenced. Two years following his diagnosis, he remains well and established on long‐term Luteinising Hormone Releasing Hormone (LHRH) therapy; his current Prostate Specific Antigen (PSA) level is 3.7 μg/L.

Discussion

Prostate cancer is the most common male cancer in the UK and the second most common cause of cancer‐related death (behind lung cancer) 1. It has a well‐recognized pattern of metastatic disease, usually involving local lymph nodes and the axial skeleton 2. However, autopsy studies demonstrate that a significant number of patients have pleural involvement at the time of death (21% of all patients with haematogenous prostatic metastases, with overall prevalence of 7%) 3; this contrasts with the rarity of clinically evident pleural disease during life (<1%).

It is extremely unusual to diagnose prostate cancer on a pleural biopsy in an asymptomatic patient, as in our report. Published case reports documenting pleural metastases from primary prostatic malignancy are few, and the majority described are spread across patients with known prostate disease 4.

Vinjamoori et al.5suggest that hepatic, pulmonary, supradiaphragmatic lymph node, and adrenal spread represent the most frequent sites for atypical metastases. In their study, pleural disease arose more frequently in patients with bone involvement; there was no correlation with pulmonary metastases.

With an ageing population, the prevalence of prostate cancer is predicted to continue to rise; currently, one in eight men in the UK will be diagnosed during their lifetime 1. Establishing an early diagnosis can improve patient outcome; physicians need to remain alert to diverse presentations of metastatic prostate cancer and the possibility of pleural involvement.

Disclosure Statement

Appropriate written informed consent was obtained for publication of this case report and accompanying images.