Pistachio green brain discolouration associated with methylene blue use: an autopsy series

Green Discoloration of Human Postmortem Brains: Etiologies and Mechanisms of Discoloration

ABSTRACT

A variety of gross discolorations of human postmortem brains is occasionally encountered and can have diagnostic implications. We describe 3 cases of green discoloration of the human brain observed on postmortem examination. Two patients who succumbed shortly after administration of methylene blue (MB) showed diffuse green discoloration that was detectable as early as 24 hours and was seen for at least 48 hours after MB administration. Green discoloration was largely in cortical and deep gray matter structures with relative sparing of the white matter. In contrast, a patient with severe hyperbilirubinemia who died after intracerebral hemorrhage showed localized bright green bile stained brain parenchyma in the areas surrounding the hemorrhage. We highlight the distinct patterns of discoloration in different causes of green brain discoloration, including MB, bile staining, and hydrogen sulfide poisoning. Recognition of these patterns by practicing pathologists can be used to differentiate between these etiologies and allow correct interpretation in both the medical and forensic autopsy settings.

Greenish-blue discoloration of the brain and heart after treatment with methylene blue

Greenish-blue discoloration of the brain and heart was observed during the autopsy of a 63-year-old woman who had been treated with methylene blue for septic shock following a traffic accident. This "pistachio" or "avatar" discoloration occurs when the colorless metabolite leucomethylene blue is oxidized to methylene blue upon exposure to atmospheric oxygen. Other clinically documented adverse effects of methylene blue include greenish-blue urine and bluish discoloration of the skin and mucosa. In medicine, methylene blue is an inhibitor of nitric oxide synthase and guanylate cyclase with different clinical applications, namely, rapid reversal of circulatory shock that is refractory to fluid administration, inotropic agents, and vasoconstrictors. Postmortem differential diagnosis with putrefaction and hydrogen sulfide poisoning should be made, and forensic pathologists should be aware of methylene blue-related greenish-blue discoloration to avoid unnecessary workup and investigations.

Turquoise Discoloration of Organs on Autopsy Secondary to Treatment of Septic Shock With Methylene Blue

Septic shock can result from the dissemination of infections and can lead to hypoperfusion secondary to vasodilation. Methylene blue can help stabilize blood pressure refractory to other measures in shock. We report a case of a 58-year-old male who died of septic shock due to Pseudomonas aeroginosa bacteremia secondary to acute folliculitis and epididymo-orchitis. He was given methylene blue for reversal of septic shock but he did not respond and expired. Autopsy findings were significant for bluish-green discoloration of organs, especially the heart, lungs, and brain during prosection secondary to methylene blue treatment. It is important to recognize artifacts of treatment and to discern them from changes due to putrefaction or the classic green pigmentation associated with Pseudomonas aeruginosa infection, such as chloronychia. The case report illustrates that circulating methylene blue and its metabolites can accumulate in the organs in a dose-related fashion, imparting an interesting turquoise to dark blue-green pigment during the autopsy. Additional studies are warranted to enable pathologists to differentiate among the pigmentation associated with Pseudomonas aeruginosa bacteremia, putrefaction, and methylene blue treatment.

Utility of autopsy in uncovering unexpected neuropathology

Autopsy rates have declined in the last several decades for a variety of reasons. The purpose of this study is to compare autopsy neuropathologic findings from 2 periods to assess the prevalence of unexpected neuropathologic findings and unexpected neuropathologic diagnoses determined to be the major cause of death. Retrospective review of autopsies with examination of the central nervous system was performed in 2007 to 2008 (n = 289) and 1984 to 1985 (n = 328). Unexpected neuropathologic diagnoses were found at autopsy in 42.4% of cases from 1984 to 1985 vs 38.8% of cases from 2007 to 2008. The neuropathology was felt to contribute to the cause of death in 22% of cases from 1984 to 1985 vs 19.7% of cases from 2007 to 2008. Unexpected neuropathologic findings were the cause of death in 5.2% of cases from 1984 to 1985 vs 3.1% of cases from 2007 to 2008. These findings underscore the continued use of brain and spinal cord examination at autopsy despite advances in "modern" medicine.