Thread by @guerreroespejo

A 71-YO therapy for multiple mieloma, voriconazole for Aspergillus fumigatus sinusitis, prophylaxis with TMP-SMX: febrile neutropenia, nodular lesion on abdominal wall
CT: pulmonary nodule unchanged in last a month
🔬biopsy of pulmonary nodule?
1/8

#Pathologists #haematology

🔬: Histiocytic process with granular basophilic cytoplasm and Michaelis-Gutmann bodies (arrows), positive for calcium with von Kossa special stain (arrowhead); findings pathognomonic for malakoplakia.

PULMONARY MALAKOPLAQUIA
2/8

doi.org/10.1093/cid/ci…
#pathTwitter

🧫of the pulmonary nodule:➖
🧫biopsy of the abdominal wall lesion: Rhodococcus equi resistant to TMP-SMX, but susceptible to rifampicin, vancomycin, azithromycin, ciprofloxacin, & imipenem.
RHODOCOCCUS EQUI SUBCUTANEOUS ABSCESS
3/8

doi.org/10.1093/cid/ci…
#microbiology

She was commenced on a prolonged course of oral rifampicin 300 mg twice daily and azithromycin 500 mg daily with resolution of the skin lesion and radiological reduction in the size of the pulmonary nodule.
4/8

#IDtwitter #MedTwitter

Rhodococcus equi is a gram-positive coccobacillus in the Nocardioform family. The most common clinical manifestation of R. equi is pulmonary, where it has been associated with nodules, pneumonia, cavitation, and abscess formation.
5/8

#Doctor #MedStudentTwitter

Malakoplakia: rare inflammatory condition most commonly associated with E. coli infection, but is only occasionally seen with R. equi infection

It occurs after ingestion of the organism by host macrophages, a failure of intracellular killing & accumulation of histiocytes.
6/8

The retained bacteria in the lysosomes result in the classically described Michaelis-Gutmann bodies, pathognomonic for malakoplakia: concentrically layered basophilic inclusions, which appear target-like & are + with periodic acid-Schiff stain & von Kossa stain.
7/8

#pathology

Rhodococcus equi is usually susceptible in vitro to trimethoprim-sulfamethoxazole, amikacin, gentamicin, vancomycin, erythromycin, rifampicin, & ciprofloxacin

It has been recommended to treat until after symptoms & radiologic findings have resolved.
8/8

#medicine #MedEd