Reply to 'Influenza follicles and their buds as early diagnostic markers of influenza: typical images' and demonstration of lymphoid follicles in the posterior pharyngeal walls of patients with mycoplasmal pneumonia.

Previously, the ‘Images in Medicine’ section of the Postgraduate Medical Journal published a letter by Miyamoto and Watanabe1 regarding an earlier article on influenza follicles that we had presented,2 informing us of an English translation of the ATLAS SAKUMA.3 We wish to express our gratitude for the images of influenza follicles presented by Miyamoto and Watanabe,1 which very clearly depict lymphoid follicles in the posterior pharyngeal wall; our images were less clear. Although the lesions we presented could have been misidentified as Yamada/Fukutomi classification type I gastric polypoid lesions, macroscopic review confirmed them to be Yamada/Fukutomi classification type II gastric polypoid lesions.

We believe that Japanese clinical physicians and patients depend on rapid influenza diagnostic kits rather than on clinical acumen (medical interviews and physical examination findings) in establishing a diagnosis of influenza. However, extensive experience is needed to ensure rigorous identification and interpretation of macroscopic findings. In this light, we appreciate the finding by Miyamoto and Watanabe that influenza follicles in the pharynx could be used as a diagnostic tool. The accuracy of the clinical criteria for diagnosing influenza4—which comprise fever plus cough, myalgia, duration <48 hours, and chills or sweats—may be improved by adding the presence of influenza follicles.

Incidentally, in our study, two patients with Mycoplasma pneumoniae infection had lymphoid follicles in the posterior pharyngeal wall; their cases are briefly presented.

Case 1

A previously healthy 21-year-old woman presented to our hospital with a 5-day history of fever (38°C at assessment), sore throat and dry cough. Lymphoid follicles with a maximum diameter of 13 mm were identified in the posterior pharyngeal wall (figure 1). A chest X-ray revealed infiltrative shadows in the right middle lung field. The patient was hospitalised and received empirical therapy with oral azithromycin 500 mg daily for 3 days and intravenous ceftriaxone 2 g daily. Her M. pneumoniae antibody titres were 1:40 (passive agglutination) on admission and 1:1280 on day 6 of hospitalisation. Therefore, she was diagnosed with mycoplasmal pneumonia.

Figure 1

Pharyngeal findings from case 1. Lymphoid follicles with diameters of 7 mm and 13 mm were identified in the posterior pharyngeal wall. The tongue depressor diameter is 18 mm (reference).

Case 2

A previously healthy 16-year-old woman had visited her primary care physician with a fever (39°C) and cough 2 days before presenting to our hospital. She was diagnosed with pneumonia (based on chest X-ray findings) and was prescribed tosufloxacin 150 mg thrice daily. However, her fever and cough persisted and she developed papules on both legs the next day (figure 2); this prompted her to visit our hospital. Lymphoid follicles with a maximum diameter of 9 mm were identified in the posterior pharyngeal wall (figure 3). A throat swab was positive for M. pneumoniae (loop-mediated isothermal amplification method), leading to a diagnosis of mycoplasmal pneumonia. The patient was prescribed oral azithromycin 500 mg daily and oral fexofenadine 60 mg twice daily for 3 days. One week later, her symptoms had resolved. An oral tosufloxacin challenge test, performed 2 months later, was negative. Therefore, the skin rash was determined to have been associated with M. pneumoniae infection.

Figure 2

Lower extremity findings from case 2. Diffuse red papules were observed over both legs.

Figure 3

Pharyngeal findings from case 2. Lymphoid follicles with diameters of 5 mm, 7 mm and 13 mm were identified in the posterior pharyngeal wall. The tongue depressor diameter is 18 mm (reference).

Lymphoid follicles in the posterior pharyngeal wall can occur as a result of viral infections such as adenovirus and echovirus3; these can be distinguished by shape from the characteristic influenza follicles as presented by Miyamoto and Watanabe.1 Although posterior pharyngeal wall lymphoid follicles do not normally occur with bacterial infections, we have presented two cases in which these lesions were observed in association with M. pneumoniae infection. These mycoplasma-associated lymphoid follicles were larger than those associated with influenza and other typical viral infections, which have a maximum diameter of approximately 10 mm. They were few in number, were teardrop-shaped with well-defined borders and exhibited flushing. Five characteristics1—diameter, shape, presence or absence of agglutination, and colouration—are used to assess the typical lymphoid follicles seen in cases of influenza virus infection. The lesions in our cases matched all characteristics except for their diameter. The frequency of lymphoid follicles in the posterior pharyngeal wall in such cases is unknown; further case studies must be accumulated.