Reactive conditions

Chapter 6 Reactive conditions

Nirag C. Jhala, Darshana N. Jhala, David C. Chhieng

TABLE OF CONTENTS

INTRODUCTION 79

PATHOGENESIS IN BRIEF 79

CLINICAL HISTORY 80

Predilections by gender 80

Predilections of laterality with pleural effusions 80

REACTIVE CONDITIONS THAT HAVE CHARACTERISTIC FEATURES OF OR COULD MIMIC CARCINOMA 82

Liver cirrhosis with activity, uremia, and acute pancreatitis 82

Pulmonary embolism and infarction 83

Systemic lupus erythematosus 83

Rheumatoid effusions 84

STUDY CASESanch 85

INTRODUCTION

Effusions of serous cavities (of the pleural space, peritoneal cavity, or pericardial space) are one of the more common manifestations of a systemic disease; however, in some instances they are reflections of regional pathology from altered homeostasis of fluid collection. It should also be noted that effusions are never ‘variations of normal’ but rather the result of an underlying pathologic process that needs to be accurately characterized both for diagnostic and for management purposes.

It is estimated that pleural effusions may affect approximately 1.3 million individuals each year in the USA. Whereas most effusions are associated with reactive conditions, it is not infrequent to find malignancies as the underlying cause, which portends a very unfavorable prognosis for patients irrespective of the site. Cytologic evaluation of effusion samples plays a key role in distinguishing reactive conditions from malignancies.¹

Coming to an accurate diagnosis for a reactive condition requires understanding of the basic pathogenesis as well as integration of clinical, radiology, and results of ancillary studies. This chapter, while providing a brief overview of earlier chapters, will provide specific examples to clarify the principles for arriving at a diagnosis.

PATHOGENESIS IN BRIEF

The principal function of physiologic (submacroscopic) fluid in cavities (pleural, peritoneal, or pericardial spaces) is to provide a frictionless surface between two membranes. Altered homeostasis, including increased production, seepage from an adjacent structure or lack of absorption of accumulated fluid into or from these spaces, leads to abnormal collection of fluid.

The following basic mechanisms may help better define the basic underlying pathogenesis for the accumulation of fluid in the serous cavities:

increased capillary hydrostatic pressure in the systemic and/or pulmonary circulation (e.g. congestive heart failure, superior vena caval syndrome)

reduced intravascular oncotic pressure (e.g. hypoalbuminemia, hepatic cirrhosis)

increased permeability of the membranes or capillaries (e.g. neoplastic disease, uremia, pancreatitis, pulmonary embolus)

altered pressures in a serous space whether associated with lack of expansion of an adjacent structure (e.g. lung from tumor) or marked increase in pleural surface area (e.g. extensive atelectasis, mesothelioma)

decreased lymphatic drainage or rupture of major lymphatic channels (e.g. chylosis, malignancy, trauma).

CLINICAL HISTORY

PREDILECTIONS BY GENDER

In general, the incidence is equal between the sexes; however, effusions associated with certain systemic diseases show some sex predilection in parallel with the general distribution of these diseases in the population. For example, it is noted that effusions associated with systemic lupus erythematosus (SLE) are observed more frequently among women, whereas effusions associated with chronic pancreatitis and rheumatoid effusions are more frequently noted in men.

PREDILECTIONS OF LATERALITY WITH PLEURAL EFFUSIONS

Systemic diseases are often associated with bilateral pleural effusions, whereas isolated unilateral effusions occur more frequently with regional pathology. Isolated right-sided pleural effusions commonly occur with subphrenic or intrahepatic abscess formation, amebic liver abscess, Echinococcus infection, cirrhosis, liver transplantation, and Meigs’ syndrome. Isolated left-sided effusions are more frequently noted with esophageal rupture, pancreatic disease, especially pancreatitis, splenic abscess, splenic infarction, diaphragmatic hernia, pericardial disease, or following coronary artery bypass surgery.

EXAMINATION OF SEROUS FLUID: A SYSTEMATIC APPROACH TO DIAGNOSIS

It is recommended that at least 30–50 mL fluid (up to 1000 mL) should be sent for cytologic analysis. For patients with bilateral pleural effusions, thoracentesis of either side provides similar information.

GROSS EXAMINATION: TYPE OF FLUID AND POSSIBLE ETIOLOGY

Fluid appearances have been classified into many categories by various observers. Of these about eight different appearances have been fairly well described with very good interobserver concordance.² These eight gross appearances comprise: watery (light yellow), serous (yellow), blood-tinged (reddish), bloody (dark red, similar to blood), purulent (pus), milky (white and less thick than pus), turbid (yellow, but viscous or cloudy), and others (brownish, greenish, black, etc.). In daily practice, effusions can be classified into two major categories: non-bloody and bloody effusions.

SPECIAL TYPES OF EFFUSIONS

Bloody effusions ^2,³

Bloody effusions (hemothorax, hemopericardium, and hemoperitoneum) are considered when the fluid is homogenously red or dark brown, shows hemosiderin pigment, and the hematocrit of the effusion is 10% or greater of the blood hematocrit. Occasional blood-tinged fluids may be noted as a result of trauma associated with a procedure. Recovery of such trauma-associated fluids shows a decreasing gradient of blood (hematocrit) as compared to a true ‘bloody effusion.’

Bloody effusions are more likely to be associated with an underlying malignancy than non-malignant conditions. The most frequent benign causes of bloody pleural effusions include parapneumonic and post-traumatic pleural insults. Table 6.1 lists some of the more frequent causes for bloody effusions.

Table 6.1 Reactive conditions associated with bloody effusions

Chylous effusion ³^–⁶

Chylothorax is the accumulation of lymphatic fluid (chyle) in the pleural space due to disruption of the thoracic duct or another major lymphatic vessel. It more commonly occurs in the pleural space rather than peritoneal or pericardial cavities. In post-traumatic cases, the fluid accumulates rapidly following injury (usually within 2–10 days), whereas those cases with gradual onset of the effusion often have a different pathologic cause, including malignancies, more specifically lymphoma. Chylous effusions should be distinguished from pseudochylous effusions since they suggest a different pathogenesis and could be observed in a myriad of other conditions, including infections such as tuberculosis.

Causes

Some of the more common causes of chylous effusions are trauma to the lymphatic vessels, occurring either from a surgical intervention (e.g. transplants, cardiac surgeries, thoracostomy tubes), thrombosis in a subclavian indwelling catheter or following non-surgical causes (e.g. ‘boxer’s chest,’ penetrating gunshots, stab wounds, blast and crush injuries). On many occasions, conditions associated with chylothorax are idiopathic. This, in fact, is one of the most common presentations associated with pleural effusion in the newborn. In adults, constrictive pericarditis, cirrhosis, and lymphangiomyomatosis have been reported to be associated with chylous effusions. They are also frequently noted with malignancies.

TRANSUDATE VS EXUDATE ^7,⁸

Distinguishing whether a fluid is a transudate or an exudate is often the initial step in the analysis of effusions and may help define the basic underlying etiopathogenesis of the effusion (Tables 6.2, 6.3, 6.4). A transudate is an ultrafiltrate of plasma associated with intact vasculature, and usually results from increased hydrostatic pressure and decreased oncotic pressure. In contradistinction, exudative fluids are generally a result of disruption of capillaries or actively altered capillary permeability. Thus, an exudative fluid more frequently parallels the plasma content. While there are many causes for exudative fluid as enumerated below, exudates are more frequently noted with malignancies and infectious/inflammatory processes (Table 6.3).

Table 6.2 Conditions usually associated with transudates

Congestive heart failure

Nephrotic syndrome

Peritoneal dialysis

Hypoproteinemia (e.g. severe starvation)

Superior vena cava obstruction

Table 6.3 Conditions associated with exudates ⁹

Table 6.4 Conditions demonstrating either exudative or transudative characteristics

Pulmonary embolism

Transudates in patients following diuretic therapy

Pericardial disease (inflammatory or constrictive)

While most described criteria provide a working guideline, it is not always possible to characterize a fluid into an exudate or a transudate. In a patient with a transudative effusion, therapy with diuretics may lead to reduction in water content and may result in altered protein concentration. Further characterizing a fluid into one of the two types (transudate or exudate) provides only a general guideline for the possible underlying etiology.

Tags: Cytopathologic Diagnosis of Serous Fluids

Jul 8, 2017 | Posted by admin in PATHOLOGY & LABORATORY MEDICINE | Comments Off

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