Reckless formalin injection in the eyelid instead of local anesthetic: case report

Accidental injection of formalin is certainly rare, but it has serious consequences in terms of morbidity and mortality. We report a case of severe ophthalmic damage due to an accidental formalin's injection in the eyelid of a three-year-old child presenting with congenital ptosis's surgical repair of her left eye. This accident has damaged the orbital region and led to upper left eyelid's necrosis, eyeball's deformation and ipsilateral cataract. In terms of our observation, we discussed consequences of this rare type of accident, and its systematic and loco-regional effects. We tried also to explain these manifestations by analyzing the metabolism process of formalin in the human body. Finally, a medico-legal implication of such accident has been illustrated according to the Tunisian law (Penal Code of the Tunisian republic 'PCT').


Introduction
Formalin is a worldwide used aqueous solution. It is composed of 35 to 40% of stabilized formaldehyde with methanol (8 to 12%) with or without formic acid (0.03%). This caustic and irritating substance is used for its bactericidal, virucidal and conservation capacity (mainly in pathology). Also, it is useful in hygiene and especially disinfection, in therapeutic stomatology (ductal pasta, resins) and industry (manufacturing of plastics, chemical, cosmetics, pharmaceuticals) [1,2]. There has been a great interest in the toxicity of formaldehyde, and most of the recent concern has centered on formaldehyde's release from urea-formaldehyde foam into the environment to be used in insulation products [1,3].
Human formaldehyde intoxication has not been adequately characterized, and there are few resources that talk about it.
However, it has many side effects. In addition to loco-regional consequences due to direct exposure by inhalation, skin contact or ingestion, there are systemic effects which can lead to multi-visceral failure [3]. We may notice different manifestations such as gastrointestinal trouble, nasal lesions, laryngeal and bronchopulmonary trouble, cell lysis and tissue necrosis following injections and atopic signs ranging from hives to anaphylactic shock [4][5][6].
Thus, formalin morbidity and mortality are recalled to justify the rules, measures and precautions of its use in caring environments [7]. This rare medico-legal case illustrates the consequences of medical malpractice which consists of an accidental injection of formalin in the upper eyelid during surgical repair of a ptosis.  Figure 4). Thus, the parents complain to the penal and the civil court alleging medical malpractice and seek a legal remedy from the court to repair economic and non economic damage.

Medical discussion
Formalin is a complex substance composed mainly of Formaldehyde (almost 40%) which is an organic compound and the simplest form of aldehyde. In view of its widespread use, exposure to formaldehyde is significant for human health because of its acute and chronic toxicity. To the Formaldehyde we add the methanol (8 to12%) which is a substance well known for its toxic properties.
This association explains the systemic toxicity of this substance, with a metabolic acidosis which depends on the exposure's quantity.
Fortunately, in our case the injected quantity was too little to pass to the systemic circulation. However, the injection of formalin in the upper eyelid had heavily loco-regional consequences in the vision prognosis with a skin necrosis, eyeball retraction and a cataract which occasioned a definite blindness. This damage is explained by the extreme reactivity of formalin with many cellular constituents and physiologic metabolites mainly with the formaldehyde (with Amino Acids, Peptides, Proteins, Nucleic Acid Bases, Nucleosides, Protein-Free DNA, Isolated nucleo-histone and with cell nuclei) [1,8].
Once injected, the formalin fixed quickly nucleic acid and amino groups of proteins causing congestive lesions which progress to hemorrhagic lesions and finally to a local cells' lysis. At this stage, inflammatory phenomena and hypersensitivity are important.
Immunologic or allergic responses in humans can be induced which can cause anaphylactic shock [5]. Loco-regional extensive necrosis of tissue is inevitable and spreads in oil spill. It is associated with In our case, the infant lost the vision function definitely and the aim of the surgery was only restorative by a skin grafting in the periorbital area and by implanting a prosthetic eye (ocular prosthesis) to improve the appearance. In case of sign of systemic passage characterized by an early multi-organ failure or possible metabolic disorders, early treatment with N-Acetyl-Cysteine, which is a safety product, can be started [7,10].

Medico-legal discussion
The focus of medical liability in Tunisia is under the law of tort, specifically negligence or inattention's fault. When a penal pursuit is recommended by the victim, the author of the fault is sued and is exposed to a penal punishment and it is an offense under Article 218 and 219 of the Penal Code of the Tunisian republic (PCT) [12].
Moreover, the culprit of the breach is sued in the civil court for a material compensation which will be fixed by the judge based on different parameters among others the expert report which will fix a rate of permanent partial disability.

Conclusion
This study probably analyzes for the first time the responsible handling procedures of formalin injection which was administered instead of local anesthetic as an accidental medical mistake. These local anesthetic bottles are commonly used to store many other products as alcohol, dental acrylic monomer, formalin, and so forth.

Competing interests
The authors declare that there is no conflict of interest.