A DIAGNOSTIC DILEMMA COMPLICATED BY SAMPLING BIAS: MUCINOUS ADENOCARCINOMA WITH SUPERIMPOSED CRYPTOCOCCAL INFECTION

Document Type

Conference Proceeding

Publication Date

6-23-2023

Publication Title

J Gen Intern Med

Abstract

CASE: A 66-year-old male with history of type 2 diabetes mellitus and coronary artery disease presented with subacute shortness of breath and pleuritic chest pain. He was recently evaluated at an outside hospital for these symptoms and transferred for additional advanced evaluation. Chest radiograph revealed a right- sided pneumothorax, and chest computed tomography (CT) scan was significant for a large right-sided hydropneumothorax and extensive pulmonary cavitary lesions bilaterally. Multiple samples of the pleural fluid were collected without significant findings. Prior to transfer, multiple biopsies of the cavitary lung lesions were obtained without yielding a diagnosis. On the fifth bronchoscopy, pathology results revealed adenocarcinoma with mucinous features and fungal cultures were significant for cryptococcus neoformans. The mucinous adenocarcinoma origin was unable to be identified on pathology, but a CT scan of the abdomen and pelvis showed an atrophic pancreas, but no definitive masses. Carbohydrate antigen 19-9 was significantly elevated. This, in conjunction with the CT findings, make a pancreatic origin the most likely source. IMPACT/DISCUSSION: Pulmonary cryptococcosis is an invasive fungal infection caused by Cryptococcus neoformans or Cryptococcus gattii. This infection is known to occur in immunocompetent or immunocompromised patients. More severe disease is often seen with immunocompromised hosts, and those with malignancy are at increased risk for cryptococcosis. The findings on chest radiograph or chest CT for pulmonary cryptococcosis and metastatic disease to the lungs are similar. For this reason, it is important to obtain biopsies and cultures of areas of concern when the definitive diagnosis remains in question to determine a diagnosis and treat accordingly. This case also highlights the phenomenon of sampling bias. Sampling bias occurs when a sample is collected in such a way that it fails to collect a representative sample and systematically favors one outcome over another. In total, the patient had five bronchoscopies with biopsies before a final histological diagnosis was made. It is of paramount importance to emphasize the need of obtaining an adequate tissue sample from multiple sites in order to attain the highest yield for a quick and accurate diagnosis. One exam finding that made the diagnosis more difficult was that the patient did not have visual evidence of a lesion while performing the bronchoscopy. A retrospective study from 2008 of patients with a diagnosis of lung cancer showed that the diagnostic yield of non-visible lesions via biopsy is 25%. CONCLUSION: Cryptococcosis is a fungal infection that can lead to pulmonary manifestations which can mimic lung cancer on imaging. The diagnosis of lung cancer can be difficult due to sampling bias. In order to increase the diagnostic yield of a biopsy, an adequate sample size from multiple sites should be obtained.

Volume

38

Issue

Suppl 3

First Page

S393

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