Open Access Case Report

Pathophysiological implication of reversed CT halo sign in invasive pulmonary mucormycosis: a rare case report

Yoichiro Okubo1, Takao Ishiwatari1, Haruka Izumi2, Fumitomo Sato3, Kyoko Aki1, Daisuke Sasai1, Tsunehiro Ando4, Minoru Shinozaki1, Kazuhiko Natori2, Naobumi Tochigi1, Megumi Wakayama1, Yoshinobu Hata3, Haruo Nakayama5, Tetsuo Nemoto1 and Kazutoshi Shibuya16*

Author Affiliations

1 Department of Surgical Pathology, Toho University School of Medicine, 6-11-1 Omori-Nishi, Ota-Ku, Tokyo 143-8541, Japan

2 Division of Hematology and Oncology, Department of Medicine, Toho University Medical Center, 6-11-1 Omori-Nishi, Ota-Ku, Tokyo 143-8541, Japan

3 Department of Chest Surgery, Toho University Medical Center, 6-11-1 Omori-Nishi, Ota-Ku, Tokyo 143-8541, Japan

4 Department of Respiratory Medicine, Japanese Red Cross Medical Center, 4-1-22, Hiroo Shibuya-Ku, Tokyo 150-8935, Japan

5 Department of Neurosurgery, Toho University Ohashi Medical Center, 2-17-6, Ohashi, Meguro, Tokyo 153-8515, Japan

6 Department of Dermatology, Peking University First Hospital, Beijing, China

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Diagnostic Pathology 2013, 8:82  doi:10.1186/1746-1596-8-82

Published: 17 May 2013

Abstract

Background

It has been accepted that reversed halo sign (RHS) appeared on a computed tomography (CT) image in immunocompromised patients indicates an invasive fungal infection, but its pathophysiology remains obscure as to what this image implies. Therefore, the present report describes detailed radiological and histopathological findings of a case of invasive pulmonary mucormycosis (IPM) presenting RHS with comparison to those from a lesion of discrete nodule caused by invasive pulmonary aspergillosis (IPA), and discusses the pathophysiological implications of this characteristic image.

Case presentation

RHS had been clinically noted at the time of recovering of bone marrow function of a 64-year-old Japanese man who had chemotherapy for his acute lymphoblastic leukemia. Histological examination of the surgically removed lung revealed a lesion of IPM. This was composed of coagulation necrosis of septa at the center of lesion with preservation of air content which was encompassed outer rim comprising triplet structure; liquefaction, consolidation, and organization from the inner to the outer layer. In addition, Micro-CT examination confirmed reticular structure and monotonous high density at the central coagulation necrosis preserving air content and surrounding consolidation, and organization lesion of the IPM lesion.

Conclusion

Our investigations suggest that RHS might be understood as a kind of immune reconstitution syndrome and be the initial and prior status of air crescent sign.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/3480054198968132 webcite

Keywords:
Reversed halo sign; Mucormycosis; Aspergillosis; Discrete nodule