Spleen contraction verified as a supportive autopsy sign of fatal hypothermia.

Postmortem diagnosis of hypothermia remains challenging even in the era of advanced virtual and molecular diagnostic technologies. Although numerous morphological findings have been described in deaths due to cold, only two-Wischnewsky spots and cold erythema (Keferstein's sign)-have traditionally been regarded as reliable autopsy indicators of fatal hypothermia. More than a century after their first description, additional supportive findings, including hemorrhages within core skeletal muscles and the inner knee sign, have expanded the spectrum of autopsy features associated with fatal cold exposure. Reactive splenic contraction, characterized by reduced splenic volume and weight, capsular wrinkling, and red-pulp anemization, has so far been reported only sporadically and has never been systematically validated in a larger human series. The present prospective controlled autopsy study investigated the occurrence and diagnostic significance of reactive splenic contraction in 54 fatalities due to hypothermia and 170 controls. The reactive splenic contraction triad was identified in 48 of 54 hypothermia cases (88.9%) and in only 2 of 170 controls (1.2%), yielding a sensitivity of 88.9% and specificity of 98.8%. Reactive splenic contraction demonstrated a remarkably strong association with fatal hypothermia (odds ratio 672.0; 95% CI 131.4-3437.2; p < 0.001). Among established autopsy findings, a statistically significant association was observed only with Wischnewsky spots (p = 0.011), whereas no significant associations were identified with cold erythema, inner knee sign, hemorrhages within core skeletal muscles, or fatty degeneration of renal tubular epithelial cells. Notably, splenic contraction was frequently present even in cases lacking advanced hemorrhagic or degenerative manifestations of hypothermia, supporting its role as an early morphofunctional response to critical cold stress. These findings indicate that reactive splenic contraction represents a novel, highly prevalent, and diagnostically valuable corroborative autopsy sign of fatal hypothermia. Its strong association with hypothermic death and relative independence from most established hypothermia markers suggest that it provides complementary diagnostic information within an integrated postmortem assessment. Moreover, early recognition of this finding may facilitate differential diagnostic reasoning, direct targeted autopsy procedures and ancillary investigations toward hypothermia, and may potentially support the further development of minimally invasive postmortem approaches, such as laparoscopic inspection of body cavities supplemented by postmortem imaging. Although reactive splenic contraction is not pathognomonic and should never be interpreted in isolation, the present findings strongly support its inclusion among corroborative morphological indicators of fatal hypothermia and its routine assessment during forensic autopsy.