Himmelmann, Andreas

Mackowiak, Philip A.

Schaffner, Andreas

Zinkernagel, Annelies S.

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ANSWER TO PHOTO QUIZ • CID 2001:32 (15 April) • 1233A N S W E R T O P H O T O Q U I ZPhilip A. Mackowiak, Section Editor(See page 1188 for Photo Quiz)Figure 1. Posteranterior (left) and lateral (right) chest radiographs obtained at presentation show a well-defined round mass in the right upper lobeReprints or correspondence: Annelies S. Zinkernagel, Department of Internal Medicine,University Hospital Zurich, Ra¨mistrasse 100, 8091 Zurich, Switzerland (annelies.zinkernagel@dim.usz.ch).Clinical Infectious Diseases 2001; 32:1233–4 2001 by the Infectious Diseases Society of America. All rights reserved.1058-4838/2001/3208-0018$03.00Diagnosis: round pneumonia due to Streptococcus pneumoniae.Fewer than 1% of cases of pneumonia manifest as pulmonaryround lesions. Because a round lesion is an early manifestationof the disease, a history of cough or fever may be absent at thetime of presentation [1]. Early in the course of infection, theinflammatory process is predominantly confined to the alveolarspace. It spreads by direct extension through the interalveolarchannels (the pores of Kohn and the channels of Lambert).This results in a lesion with a nonsegmental distribution andsmooth borders. Later, with centrifugal and peribronchialspread, the pneumonia lesion becomes segmental or lobar, andthe typical appearance is seen on a radiograph [2, 3].The pathways of collateral ventilation (the pores of Kohn)are poorly developed in children. Children also have moreclosely apposed connective tissue septae and smaller alveoli thanadults do. These factors work together to produce more-com-pact confluent areas of pulmonary consolidation, without thesofter margins that are evident in the typical infiltrates seen inadults [4]. They also result in a slower progression of diseaseand increase the chance of detecting round pneumonia. There-fore, round pneumonia is more often seen in children than inadults.The organism that most frequently causes round pneumoniahas been found to be Streptococcus pneumoniae, followed, indescending order of frequency, by Klebsiella pneumoniae, Hae-mophilus influenzae, Coxiella burnetti, and Mycobacterium tu-berculosis. Fungal infections, hydatid cysts, and lung abscessesmay have a similar appearance on chest radiographs [5]. Al-though malignant lesions are the most common cause of pul-monary round lesions in adults, one should consider infectiousprocesses, malformations, and round atelectasis, as well as be-nign tumors, in any differential diagnosis of pulmonary masslesions.1234 • CID 2001:32 (15 April) • ANSWER TO PHOTO QUIZFigure 2. Posteroanterior chest radiograph obtained 24 h after admissionshows an infiltrate in the region of the apicoposterior segment of theupper lobe, as seen in a classical pneumonia.Our patient had pneumococcal pneumonia with sepsis andoliguria (figure 1). Cultures of blood samples yielded S. pneu-moniae. She was successfully treated with amoxicillin for 10days and with aggressive volume resuscitation because of hy-potension with prerenal azotemia. A chest radiograph obtained24 h after admission showed classic lobar pneumonia (figure2).Annelies S. Zinkernagel, Andreas Schaffner, and Andreas HimmelmannDepartment of Internal Medicine, University Hospital Zurich, ZurichReferences1. Wagner AL, Szabunio M, Hazlett KS, Wagner SG. Radiologic manifes-tations of round pneumonia in adults. Am J Roentgenol 1998; 170:723–6.2. Pandya K, Tuchschmidt J, Gordonson J, Boylen CT. Mass lesion in anintravenous drug user. West J Med 1989; 150:95–6.3. Soubani AO, Epstein SK. Life-threatening round pneumonia. Am JEmerg Med 1996; 14:189–91.4. McLennan MK. Radiology rounds. Can Fam Physician 1998; 44:757–9.5. Torres H, Noronha PA. A healthy infant with a round pneumonia. HospPract 1984; 19:57–61.

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