Forensics in dermatology: Part II

[Differential diagnosis of common nail disorders in childhood]

BACKGROUND

Correct diagnosis of nail changes in childhood may be challenging. Knowing the anatomy of the nail apparatus and some pathophysiologic principles helps to categorize nail disorders correctly.

OBJECTIVES

This article gives a structured overview of nail disorders in childhood, thus, facilitating correct diagnosis of nail abnormalities in childhood.

MATERIALS AND METHODS

A review of literature and our own experience are presented.

RESULTS

In the first part we present fundamental anatomical characteristics of the nail apparatus based on embryonal development of the nails. In the main part we categorize nail disorders according to clinical presentation: transient nail changes, congenital nail abnormalities, infectious diseases of the nails, nail changes in the context of chronic inflammatory skin diseases, pigmented nail changes, tumors and nail changes due to trauma.

Skin lesions, differential diagnosis and practical approach to potential survivors of torture

As the international refugee crisis has reached new proportions (BMJ, 355, 2016 and i5412), survivors of torture increasingly present in treating physicians with an array of acute or chronic skin lesions. Physicians should be aware of common presentations and likely differential diagnoses in order to avoid mislabelling or under-recognizing torture. Survivors of torture also frequently suffer from psychological sequelae, such as post-traumatic stress disorder, and appropriate referrals are essential in order to improve recovery trajectory. Skin sequelae are the most common physical findings of torture. Not all skin lesions seen in tortured survivors are due to perpetrator inflicted injuries, and many dermatological conditions can mimic lesions typical of torture, as can scars as a result of folk remedies or cultural practices specific to geographical regions. Medical documentation of torture includes injury and lesion description. While forensic dermatology and other forensic specialties use an injury description taxonomy, and the standard dermatologic taxonomy uses an anatomic description, they are complementary sciences for lesions inflicted by torture. This results in an opportunity for learning across disciplines in order to improve evidence documentation for survivors of torture. This article describes features of common skin lesions consistent with torture, including their clinical appearances, differential diagnoses, patterns of injury and appropriate clinical descriptions.

Discordance of Gross and Histologic Findings in Estimating the Range of Fire of Gunshot Wounds

Forensic pathologist use soot and/or stippling surrounding entrance gunshot wounds in categorizing range of fire. If absent, some pathologists suggest utilizing histology when the range is diagnostically critical. This study investigates the concordance of macroscopic and microscopic findings in estimating range of fire by evaluating gunshot entrance and exit wounds made through human tissue analogs at defined distances using two handgun calibers. Examination of over 150 entrance wounds verified the ease of visually detecting soot from a muzzle distance of contact to 1 foot (30.5 cm), and its absence at 9 feet (274.3 cm). Distinctly apparent was bullet wipe surrounding the entrance wounds regardless of muzzle distance. Although variations existed, dark material was histologically identified in many skin, soft tissue, and bone sections at all ranges with both calibers. These nonparallel results decrease the dependability of histology for range of fire estimation and reinforce using gross observation.

Forensic study of skin postmortem changes as a supplementary test to determine postmortem interval (first 78 hours)

Introduction. Determining the postmortem interval is usually based on macroscopic-morphological criteria (cadaveric phenomena); some other objective methods are often difficult to access in daily practice; therefore we analyze the usefulness of the histopathological examination of the skin as a supplementary method for determining the postmortem interval. Materials and methods.  23 patients and 92 skin biopsies were analyzed. All samples were taken in a maximum time of 6 h postmortem. Biopsies were classified into 4 groups according to the postmortem interval, with 23 biopsies in each group: 1 (1 to 6 h.); 2 (25 to 30 h.); 3 (49 to 54 h.); 4 (73 to 78 h); 21 histological criteria were analyzed with Fisher test and principal component analysis. Results.  Skin biopsies of 23 corpses (mean age 51.6 years, 15 males and 8 females) were studied. 21 histological criteria were analyzed by Fisher test; statistical significance (p <0.001) with a reliability of 94.61% was achieved in 15 parameters. With the 15 selected parameters, a principal component analysis established that there were differences among the 4 analyzed groups. Conclusions. The skin histological changes may be used as a supplementary parameter in the forensic evaluation of the early postmortem interval.

Distinction between forensic evidence and dermatological findings

The external examination after death requires knowledge in forensics/pathology, dermatology, as well as associated diseases and age-related alterations of the skin. This article highlights some findings with forensic evidence versus dermatological findings. The lectures in forensic medicine should be structured interdisciplinarily, especially to dermatology, internal medicine, surgery, pathology, and toxicology in order to train the overlapping skills required for external and internal postmortem examinations.

[Anatomy, biology, physiology and basic pathology of the nail organ]

The nail is the largest skin appendage. It grows continuously through life in a non-cyclical manner; its growth is not hormone-dependent. The nail of the middle finger of the dominant hand grows fastest with approximately 0.1 mm/day, whereas the big toe nail grows only 0.03-0.05 mm/d. The nails' size and shape vary characteristically from finger to finger and from toe to toe, for which the size and shape of the bone of the terminal phalanx is responsible. The nail apparatus consists of both epithelial and connective tissue components. The matrix epithelium is responsible for the production of the nail plate whereas the nail bed epithelium mediates firm attachment. The hyponychium is a specialized structure sealing the subungual space and allowing the nail plate to physiologically detach from the nail bed. The proximal nail fold covers most of the matrix. Its free end forms the cuticle which seals the nail pocket or cul-de-sac. The dermis of the matrix and nail bed is specialized with a morphogenetic potency. The proximal and lateral nail folds form a frame on three sides giving the nail stability and allowing it to grow out. The nail protects the distal phalanx, is an extremely versatile tool for defense and dexterity and increases the sensitivity of the tip of the finger. Nail apparatus, finger tip, tendons and ligaments of the distal interphalangeal joint form a functional unit and cannot be seen independently. The nail organ has only a certain number of reaction patterns that differ in many respects from hairy and palmoplantar skin.