CNS Histoplasmosis as a Gliosarcoma mimicker: The diagnostic dilemma of solitary brain lesions

Abstract

Histoplasmosis is usually a benign, self-limited disease with lungs predilection. However, it might manifest as a disseminated disease in immunocompromised individuals. The involvement of the central nervous system (CNS) accounts for about 5-10% of cases with disseminated disease. Isolated histoplasmosis of the CNS is rare, and the literature shows only a few reported cases. By imaging studies, it usually presents as an isolated ring-enhancing lesion. Its spectrum of symptoms ranges from acute severe infection to progressive chronic meningitis, which delays the initial diagnosis, correct work-up and initiation of appropriate therapy. We present a case of a 57-year-old man from the Midwest of the United States who misdiagnosed with Gliosarcoma in 2019, for which he underwent appropriate management for Gliosarcoma. Presented for follow-up after new neurological symptoms; worsening in ring-enhancing brain lesions was found on magnetic resonance image MRI. After a re-examination of surgical pathological cases, histoplasmosis of the CNS was diagnosed. Failure of diagnosis CNS histoplasmosis early can lead to poor outcome and decrease chances of recovery.

Keywords: CNS fungal infection; Gliosarcoma; Histoplasmosis.

Fig. 1

Cranial Histoplasmosis lesions: Initial magnetic resonance image of the brain at seven months after the first craniotomy; showed two new rim-enhancing lesions, measuring 11 and 5 mm in the greatest dimension. The largest mass was in the left cerebellar region, while the smaller lesion was in the left temporal lobe. picture on the left: 6 × 4.2 × 3 mm in left cerebellar (white arrow). Picture on right: left posterior inferior temporal lobe approximately 5 mm in diameter (orange arrow). (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.)

Fig. 2

Magnetic resonance image of the brain thirteen months after his first craniotomy. Left: 17 x 21x 15 mm ring enhancing lesion in left cerebellar (white arrow). Right: same 6 mm rim-enhancing lesion in the left temporal occipital region (green arrow). (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.)

Fig. 3

Histopathological specimen and stain from the patient's 2nd craniotomy samples. A. Hematoxylin & Eosin (H&E) stains show cellular foci composed of fibroblast, histiocytes, and glial cells with hyperchromatic nuclei, originally concerning for glioma. B. Hematoxylin & Eosin (H&E), stains serpentine basophilic necrosis originally concerning for palisading necrosis of a glioblastoma. In B (inset), tissue voids within histiocytes were suspicious for occult yeast fungal forms. C,D Grocott methenamine silver (GMS) and Periodic Acid Schiff Stain for fungus (PAS-F) highlights the walls of numerous small oval-to-round yeast forms growing in clusters within regions of necrosis (C) and within histiocytes within regions of inflammation (D). Additionally, mucicarmine stain was ordered and confirms the absence of capsule, as would be seen in Cryptococcus neoformans. Tissue cultures grew Histoplasmosis capsulatum.

Fig. 4

Basic blood work up obtained at thirteen months after the first craniotomy.

Fig. 5

Magnetic resonance image of the brain five months after finishing 1st round of amphotericin induction, and while being on therapeutic itraconazole, pictures show a new right-side lesion at posterior centrum semiovale(white arrow) extending to the posterior horn of the right lateral ventricle (green arrow) and into the body of the corpus callosum (blue arrow). (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.)