Logo American Journal of Case Reports

Call: 1.631.629.4328
Mon-Fri 10 am - 2 pm EST

Contact Us

Logo American Journal of Case Reports Logo American Journal of Case Reports Logo American Journal of Case Reports

15 June 2023: Articles  Brazil

Chocolate-Colored Pseudochylothorax in a Woman with a History of Pleuropulmonary Tuberculosis

Challenging differential diagnosis, Rare disease

Laura Braga Monnerat ORCID logo1ABEF, Elisa Barbosa Louzada1ABEF, Vanessa Godinho Souza Braga1ABEF, Mariana Soares da Cal ORCID logo1ABEF, Agnaldo José Lopes ORCID logo123ABEFG*, Thiago Thomaz Mafort ORCID logo12ABEF

DOI: 10.12659/AJCR.939473

Am J Case Rep 2023; 24:e939473




BACKGROUND: Pseudochylothorax is a rare entity, with only a few hundred case reports worldwide. It presents as a pleural effusion rich in lipids, typically with a cloudy, milky appearance. The diagnosis is made based on the levels of cholesterol and triglycerides in the pleural fluid.

CASE REPORT: This is the case report of a 55-year-old woman with a history of pleuropulmonary tuberculosis that was treated in childhood, with a new infection and treatment in adulthood that evolved to a left pleural effusion. Thirteen years after completing her last treatment for tuberculosis, the patient developed general fatigue and dyspnea on exertion. Computed tomography of the chest confirmed the presence of a pleural collection in the same location as in adolescence, suggesting a chronic evolution with encystation. The patient underwent ultrasound-guided diagnostic thoracentesis. The collected liquid was thick, chocolate-colored, with the following biochemical characteristics: pH, 7.3; glucose, 37.9 mg/dL; LDL, 2059.8 IU/L; total protein, 8.8 mg/dL; triglycerides, 90 mg/dL; adenosine deaminase, 56 U/L; and cholesterol, 300 mg/dL. The effusion was characterized as a pseudochylothorax. The cell count showed 631 000 leukocytes/µL, with 87.9% polymorphonuclear cells. Owing to the patient’s respiratory symptoms, an evacuatory thoracentesis was performed. After the procedure, the patient’s symptoms improved.

CONCLUSIONS: Although pseudochylothorax is a rare condition, its possibility must always be kept in mind to avoid the hazards of misdiagnosis. In addition to the ‘classic’ milky and machine oil appearance, a chocolate-colored appearance should also serve as a clue to the diagnosis of pseudochylothorax.

Keywords: pleural diseases, Pleural Effusion, thoracentesis, Adolescent, Female, Humans, Middle Aged, chocolate, Pleura, Exudates and Transudates, Dyspnea


Pseudochylothorax, also known as cholesterol effusion or chyliform effusion, is one of two types of lipid pleural effusions. This group of effusions, composed of chylothorax and pseudo-chylothorax, is usually unilateral [1,2] and can be recognized by the high lipid content and characteristic cloudy or milky appearance [3,4]. Although similar, chylothorax and pseudochylothorax represent distinct entities with different etiologies, clinical implications, and treatments [5–9]. Chylothorax was first described by Bartolet in 1633 as the accumulation of chyle in the pleural space and is usually associated with rupture or obstruction of the thoracic duct [10]. It is characterized by a lipid-rich fluid with a high content of triglycerides (>110 mg/dL), the presence of chylomicrons, and the absence of cholesterol crystals [1,2,9]. Pseudochylothorax was first described by Bruce F. Weems in 1918 as the accumulation of a cholesterol crystal-rich fluid within the pleural space [11]. Although pseudochylothorax is also composed of a lipid-rich fluid, it has a high cholesterol content (>200 mg/dL) and a lower triglyceride concentration (<110 mg/dL). It often has cholesterol crystals on microscopy, which cannot be attributed to thoracic duct involvement [4,12].

Analysis of pleural fluid with the measurement of cholesterol and triglyceride levels is of paramount importance for the distinction between the two types of lipid effusions [7]. Confirmation of the effusion type is assessed mainly by the absence of chylomicrons in the pseudochylothorax fluid [13]. Because pseudochylothorax is a rare entity, epidemiological studies of pseudochylothorax are limited, but there have been a few hundred case reports worldwide [5].

The main clinical conditions that predispose patients to the development of pseudochylothorax are tuberculosis and rheumatoid arthritis. Rarer causes include empyema with incomplete treatment, hemothorax, pleuropulmonary paragonimiasis, alcoholism, syphilis, and hepatopulmonary echinococcosis [7]. Additionally, rare malignant causes of pseudochylothorax exist, including lung cancer and, more recently reported, pleural mesothelioma [14]. Other reported causes are yellow nail syndrome, iatrogenesis, and Demos-Meigs syndrome [5]. Rheumatoid-associated pseudochylothorax can have a relatively rapid onset, with a median duration of symptoms of 15 months, and does not show typical pleural thickening [15,16]. Clinically, patients with pseudochylothorax can be asymptomatic in up to one-third of cases [17] or can present symptoms of dyspnea and chest pain [5]. Symptoms can be associated with the underlying disease or with the inflammatory and restrictive process of the pleura itself. The pleura is often thickened and can present calcifications [5]. The diagnosis of chyliform effusion is based on the analysis of the aspirated fluid in thoracentesis and should be considered a diagnostic hypothesis in cases of chronic pleural effusions associated with fibrosis and pleural thickening [7].

Case Report

The patient was a 55-year-old woman with a history of pulmonary tuberculosis treated at the age of 10 years without complications with a combination of isoniazid, rifampicin, and pyrazinamide. She had a history of childhood asthma and plantar psoriasis, with regular topical use of clobetasol propionate for dermatologic disease to date. At 40 years of age, she presented with a new pulmonary infection due to tuberculosis, which was treated for 1 year, owing to the development of drug-related hepatitis related to the therapeutic regimen (combination of isoniazid, rifampicin, ethambutol, and pyrazinamide), requiring an alternative regimen (combination of streptomycin, ethambutol, and ofloxacin). During the second treatment, the patient experienced a sudden onset of pleuritic pain. A chest computed tomography (CT) was performed and showed the presence of pleural effusion on the left, but was not addressed at this time. Five days after CT, she again became asymptomatic and remained so until the end of the tuberculosis treatment. Thirteen years after completing the tuberculosis treatment, she developed general fatigue and dyspnea on exertion. Symptoms progressively worsened over 3 months. At that time, a chest X-ray revealed homogeneous hypotransparency in the lower half of the left hemithorax with effacement of the costophrenic sinus, suggesting pleural effusion. In light of this finding, a new CT of the chest was requested. Results of the chest CT confirmed the presence of pleural collection in the same site where the previous CT had shown pleural effusions 3 months prior, suggesting chronic evolution with encystation. In addition, thickening of the pleural leaflets with foci of calcification on the left was observed and associated with reduced volume of the ipsilateral lung (Figure 1).

The patient was then admitted and on day 1 of admission, she underwent diagnostic ultrasound-guided thoracentesis. The liquid collected was thick, chocolate-colored (Figure 2), with the following biochemical characteristics: pH, 7.3; glucose, 37.9 mg/dL; lactate dehydrogenase (LDL), 2059.8 IU/L; total protein, 8.8 mg/dL; triglycerides, 90 mg/dL; adenosine deaminase, 56 IU/L; and cholesterol, 300 mg/dL. These levels characterized the effusion as a pseudochylothorax. Cellularity showed 631 000 leukocytes/µL, with 87.9% polymorphonuclear cells. The culture for common organisms was negative. Assessment of acid-fast bacilli and the culture for Mycobacterium tuberculosis cultures were also negative. Similarly, the polymerase chain reaction (PCR) for M. tuberculosis (GeneXpert) and the direct search and culture for fungi were also negative. Cytology of the pleural fluid showed cell debris, some lymphocytes and rare red blood cells, which were negative for malignant cells.

Fecal sample and serum IgG serology for Entamoeba histolytica was negative. Due to logistical issues at our institution, pleural biopsy was unfortunately not performed.

It is noteworthy that during the second treatment of tuberculosis, the patient did not undergo thoracentesis or any treatment for pleural effusion, although she successfully completed the drug treatment with considerable clinical improvement. Owing to the patient’s respiratory symptoms persisting even after 3 days of hospitalization, evacuation thoracentesis was performed to promote improvement of respiratory symptoms. After the procedure, the patient showed improvement of symptoms and remained asymptomatic. She was discharged 5 days after admission. A point-of-care lung ultrasound performed 6 months after presentation showed no recurrence of the pleural effusion.


Although pseudochylothorax has most commonly been described with a cloudy, milky appearance similar to chylous effusions, it is worth noting that it can appear opalescent in many cases, with a dark yellow color described as having a “machine oil appearance” [14,18]. Despite the chocolatey appearance of the liquid in this case report not being typical, a case series of chyliform effusions was published, in which 1 patient also presented a chocolate-colored effusion [17]. The patient in question was a man born in 1920 who was diagnosed and treated for pulmonary tuberculosis with pneumothorax and repeated courses of antibiotic therapy. He developed a chocolate-colored effusion with high cholesterol content that required relief thoracentesis due to effusion recurrence and respiratory symptoms [17].

The liquid collected from a patient with pseudochylothorax usually has a cholesterol concentration greater than 200 mg/dL, a triglyceride level less than 110 mg/dL, and a cholesterol/triglyceride ratio >1. It may or may not contain cholesterol crystals on microscopy [5,7,13]. The biochemical analysis often shows exudative fluid, with pH <7.2, glucose <60 mg/dL, protein concentration ranging between 4 and 7 g/dL, and high LDL. Neutrophils predominate among the cell types [13], showing a neutrophilic inflammatory process. In the present case, the characteristics of the fluid were compatible with pseudo-chylothorax. Although a pleural fluid cholesterol value greater than 200 mg/dL is strongly suggestive of pseudochylothorax, the evidence to support this diagnostic cutoff is limited [19]. In fact, approximately a quarter of cases of pseudochylothorax present a cholesterol value in the pleural fluid below 200 mg/dL and some cases can reach values as low as 120 mg/dL [5].

The pathophysiology of chyliform effusions is not yet fully understood, but the main hypothesis for the development of pleural effusion is based on inflammatory processes with chronification that evolve to visceral and parietal leaflet stiffening and fibrosis [17]. These changes hinder the physiological drainage of pleural fluid, favoring the accumulation of cell lysis products, especially neutrophils and erythrocytes. These neutrophils and erythrocytes have high levels of cholesterol and lecithin-globulin complexes in their cytoplasm, which would be the source of the high levels of lipids in the liquid [7]. Another possible explanation is that cholesterol is derived from serum lipoproteins, which would also be trapped in the pleural space and consequently be transferred to high-density lipoproteins due to the stiffening and fibrosis of the leaflets [7]. The patient reported here belongs to the group of patients with a chronic inflammatory process in the pleura. After the second time the patient was treated for tuberculosis, pleural effusion had already been observed, but this was not addressed. It is interesting to note that despite not approaching the liquid, it seems that it remained sterile, since the direct test cultures and PCR for M. tuberculosis were negative in the current analysis of the liquid.

The management of pseudochylothorax depends on the underlying disease with which it is associated and its appropriate treatment [7,13,20]. Management evolves favorably in most cases, without the need for intervention [18]. Patients who present symptoms due to the mechanical effects of pleural effusion, such as restriction or dyspnea [7] or a progressive increase in the amount of pleural fluid, can undergo relief thoracentesis. In cases of recurrence of the effusion and symptoms after drainage, decortication surgery [7,13,20] or pleurodesis [13] should be performed, with consideration to the knowledge that repeated drainage can generate complications such as empyema and pleurocutaneous fistulas. It is extremely important to treat and/or screen for rheumatoid arthritis and tuberculosis in patients diagnosed with pseudochylothorax since these are the 2 main etiologies of this type of pleural effusion [7]. The patient presented here was treated with evacuatory thoracentesis, which was followed by a good evolution. Notably, we chose this procedure because it is less invasive and does not require hospitalization. Another factor that contributed to this choice was the COVID-19 pandemic, as the patient was initially evaluated at a time when many hospital beds in Brazil were occupied with patients with COVID-19. Finally, it is worth highlighting primary effusion lymphoma-like lymphoma (PEL-LL), which is a possible complication of long-standing tuberculous pleuritis [21]. PELLL is a rare B-cell lymphoma characterized by the expression of pan B-cell markers (CD19, CD20, or CD 79a). Diagnosis of PELLL requires a long period of time because it follows a unique progression of disappearance and recurrence of the pleural effusion [21,22]. As a pleural biopsy was not performed, PEL-LL was not completely ruled out in the patient’s presentation.

Although chylothorax and pseudochylothorax are rare entities, they should be considered during the investigation of a patient with pleural fluid. The diagnosis of these effusions is important because each has different etiologies and management. Identifying the etiology can also help in the diagnosis and correct treatment of the underlying disease [5]. Cholesterol-rich effusions should be looked for during the analysis of the pleural fluid by analyzing the lipid content because this can aid in the diagnosis [5]. The management of patients with this type of pleural effusion can range from simple procedures, such as evacuatory thoracentesis, to more complex procedures, such as pleuroscopy with or without pleural drainage. The choice of procedure will depend on the symptoms, the amount of fluid, and the recurrence of pleural effusion after the initial thoracentesis.


Although pseudochylothorax is a rare condition, its possibility must always be kept in mind to avoid the risk of misdiagnosis. This becomes more relevant for clinicians, as the main causes of pseudochylothorax are benign conditions. When clinicians are faced with pleural lipid effusion, the differential diagnosis of chylothorax and pseudochylothorax must be made, especially in cases caused by thoracic duct obstruction due to malignancies, trauma, surgical procedures, superior vena cava thrombosis, and heart insufficiency. In addition to the classic milky appearance and machine-oil appearance, a chocolate-colored appearance should serve as a clue to the diagnosis of pseudochylothorax.


1.. Merrigan BA, Winter DC, O’Sullivan GC, Chylothorax: Br J Surg, 1997; 84(1); 15-20

2.. Staats B, Ellefson R, Budahn L, The lipoprotein profile of chylous and nonchylous pleural effusions: Mayo Clin Proc, 1980; 55(11); 700-4

3.. Doerr CH, Miller DL, Ryu JH, Chylothorax: Semin Respir Crit Care Med, 2001; 22(6); 617-26

4.. Sassoon CS, Light RW, Chylothorax and pseudochylothorax: Clin Chest Med, 1985; 6(1); 163-71

5.. Lama A, Ferreiro L, Toubes ME, Characteristics of patients with pseudochylothorax: A systematic review: J Thorac Dis, 2016; 8(8); 2093-101

6.. Riley LE, Ataya A, Clinical approach and review of causes of a chylothorax: Respir Med, 2019; 157; 7-13

7.. Huggins JT, Chylothorax and cholesterol pleural effusion: Semin Respir Crit Care Med, 2010; 31(6); 743-50

8.. Braun CM, Ryu JH, Chylothorax and pseudochylothorax: Clin Chest Med, 2021; 42(4); 667-75

9.. Agrawal V, Doelken P, Sahn SA, Pleural fluid analysis in chylous pleural effusion: Chest, 2008; 133(6); 1436-41

10.. Johsman W, Chylothorax. Brief review of literature: Report of 3 nontraumatic cases: Ann Intern Med, 1944; 21; 669

11.. Weems BF, Cholesterohydrothorax, observations upon a case: Am J Med Sci, 1918; 156(1); 20

12.. Hillerdal G, Chylothorax and pseudochylothorax: Eur Respir J, 1997; 10(5); 1157-62

13.. Agrawal V, Sahn SA, Lipid pleural effusions: Am J Med Sci, 2008; 335(1); 16-20

14.. Hassan M, Daneshvar C, Corcoran JP, A ‘pseudochylopneumothorax’at presentation of mesothelioma: Arch Bronconeumol, 2022; 58(2); 173

15.. Wrightson JM, Stanton AE, Maskell NA, Pseudochylothorax without pleural thickening: Time to reconsider pathogenesis?: Chest, 2009; 136(4); 1144-47

16.. Agrawal A, Chandermani , Madaan H, Yadav S, Rheumatoid arthritis complicated by pseudochylothorax without pleural thickening: A diagnostic challenge for clinicians: Indian J Chest Dis Allied Sci, 2016; 58(1); 59-61

17.. Hillerdal G, Chyliform (cholesterol) pleural effusion: Chest, 1985; 88(3); 426-28

18.. Madani Y, Fowler RW, Corcoran JP, An opalescent pleural effusion: J Bronchol Intervent Pulmonol, 2019; 26(2); e16-e17

19.. Hamm H, Pfalzer B, Fabel H, Lipoprotein analysis in a chyliform pleural effusion: Implications for pathogenesis and diagnosis: Respiration, 1991; 58(5–6); 294-300

20.. Ryu JH, Tomassetti S, Maldonado F, Update on uncommon pleural effusions: Respirology, 2011; 16(2); 238-43

21.. Hayashino K, Meguri Y, Yukawa R, Primary effusion lymphoma-like lymphoma mimicking tuberculous pleural effusion: three case reports and a literature review.: Intern Med., 2022 [Online ahead of print]

22.. Koeda C, Sato T, Matsumoto Y, A unique case of primary effusion lymphoma-like lymphoma showing disappearance and recurrence of the body cavity effusion.: J Gen Fam Med, 2017; 18(1); 38-41

In Press

Case report  Italy

Morbihan Disease: A Rare Case of Periorbital Bilateral Edema with Histopathological Findings of Chronic Inf...

Am J Case Rep In Press; DOI: 10.12659/AJCR.943421  

Case report  Poland

Lung Lesions: Differential Diagnoses Beyond Cancer

Am J Case Rep In Press; DOI: 10.12659/AJCR.943798  

Case report  USA

Sinus Node Dysfunction Triggered by Tonsillar Abscess: Effects of Vagal Nerve Compression

Am J Case Rep In Press; DOI: 10.12659/AJCR.943944  

Case report  China (mainland)

Genome Sequencing Analysis of a Rare Case of Blood Infection Caused by Flavonifractor plautii

Am J Case Rep In Press; DOI: 10.12659/AJCR.943920  

Most Viewed Current Articles

07 Mar 2024 : Case report  USA 37,955

Neurocysticercosis Presenting as Migraine in the United States

DOI :10.12659/AJCR.943133

Am J Case Rep 2024; 25:e943133


10 Jan 2022 : Case report  Germany 31,037

A Report on the First 7 Sequential Patients Treated Within the C-Reactive Protein Apheresis in COVID (CACOV...

DOI :10.12659/AJCR.935263

Am J Case Rep 2022; 23:e935263

19 Jul 2022 : Case report  Saudi Arabia 17,673

Atlantoaxial Subluxation Secondary to SARS-CoV-2 Infection: A Rare Orthopedic Complication from COVID-19

DOI :10.12659/AJCR.936128

Am J Case Rep 2022; 23:e936128

23 Feb 2022 : Case report  USA 17,528

Penile Necrosis Associated with Local Intravenous Injection of Cocaine

DOI :10.12659/AJCR.935250

Am J Case Rep 2022; 23:e935250

Your Privacy

We use cookies to ensure the functionality of our website, to personalize content and advertising, to provide social media features, and to analyze our traffic. If you allow us to do so, we also inform our social media, advertising and analysis partners about your use of our website, You can decise for yourself which categories you you want to deny or allow. Please note that based on your settings not all functionalities of the site are available. View our privacy policy.

American Journal of Case Reports eISSN: 1941-5923
American Journal of Case Reports eISSN: 1941-5923