Abstract In wounds that are inflicted at least 60 min be- fore death, histamine levels can increase up to 100%. This functional effect might have a morphometric counterpart. Mast cells play a crucial role in acute inflammatory reac- tions and in the healing process of wounds. Therefore, the density of these cells was immunohistochemically as- sessed in tissue from 20 healthy controls (Group 1), 20 vi- tal skin lesions (Group 2) (age range: a few seconds to 1 h), and 20 postmortem lesions (Group 3). A piece of skin close to the vital lesion was also obtained from the homo- lateral part of the body (Group 4). Mast cell density was significantly higher at the level of the vital lesions (11.28±2.44) than elsewhere (healthy controls 7.66±1.27, postmortem lesions 4.13±1.46, skin close to the vital le- sions 4.88±1.59). No differences were found between the values assessed in the skin samples close to the vital le- sions and in those in the postmortem lesions. Therefore, mast cell richness in the vital lesions exhibited a propor- tional morphological correlation with previously detected histamine values in cutaneous vital lesions. These results suggest that the detection of mast cells with immunohisto- chemical techniques can lead to a high level of discrimi- nation (based on statistical data) between antemortem and postmortem lesions. This method could also be used to as- certain the vitality of lesions. Keywords Immunohistochemistry · Mast cells · Postmortem lesions · Vital lesions Introduction In many cases, the forensic pathologist is not able to ar- rive at a diagnosis of the vital origin of some wounds. In forensic case work investigations, there are many situa- tions where the vital or non-vital origin of the wound is able to be established using only macroscopical examina- tion. Other circumstances require additional studies to ob- tain a more exact diagnosis of tissue vitality. Sensitive methodology must be employed so as to detect the nu- merous substances involved in the first steps of an inflam- matory reaction [1]. During the past 50 years, the devel- opment of histochemistry, enzymology, and biochemistry, and the application of these studies to the diagnosis of wound vitality have allowed for a partial solution to the problem [1, 2, 3, 4, 5]. It is well known that histamine, an important vasoac- tive amine, participates in an acute inflammatory reaction [6]. Endogenous histamine is responsible for initiating vascular changes that involve vasodilatation and increased vascular permeability and other mechanisms are then re- quired to maintain them [7]. In 1965 Fazekas and Virágos-Kis [8] observed that there was an increase in the free histamine content in marks caused by hanging. Their work encouraged a num- ber of forensic pathologists to begin biochemical studies on the possible use of the histamine content in the skin to differentiate antemortem from postmortem wounds and to estimate lesion vitality [9, 10, 11]. In particular, Berg and Bonte demonstrated that the histamine levels in vital skin wounds inflicted at least 60 min before death could in- crease up to 100% [12]. We hypothesized that these biochemical events might also have a histologic correlation: a quantitative alteration in the number of histamine secreting cells, such as mast cells (MC) [13, 14], could also take place. We therefore carried out an in situ immunohistochemical study to compare the density of MC in vital wounds that had been inflicted from a few seconds to 1 h before death (according to hospital staff), and in postmortem lesions. A. Bonelli · S. Bacci · G. B. Vannelli · G. A. Norelli Immunohistochemical localization of mast cells as a tool for the discrimination of vital and postmortem lesions Int J Legal Med (2003) 117 : 14–18 DOI 10.1007/s00414-002-0304-0 Received: 24 September 2001 / Accepted: 28 February 2002 / Published online: 7 November 2002 ORIGINAL ARTICLE A. Bonelli (✉) · S. Bacci · G.A. Norelli Department of Anatomy, Histology, and Forensic Medicine, Sect. of Forensic Medicine, Università degli Studi di Firenze, Viale Morgagni 85, Florence, Italy e-mail: assic@cesit1.unifi.it, Tel.: +39-55-415525, Fax: +39-55-4277403 G.B. Vannelli Department of Anatomy, Histology, and Forensic Medicine, Section of Anatomy, Università degli Studi di Firenze, Florence, Italy © Springer-Verlag 2002