A patient of about 50 years went to a chinese hospital suffering from a skin lesion that caused him pain in the wrist. He went through several clinics and they all concluded that it was a eczema. Therefore, they proceeded to treat him with steroid creams and antihistamine pills. If it was a conventional eczema, the problem would have remitted quickly with this treatment. But he didn’t. That’s why in the Fujian Medical University was subjected to a second much more exhaustive study. And with him it was shown that this injury was not an eczema, but the result of a piece of caterpillar inserted under its skin.
They came to that conclusion for two reasons. On the one hand, because the microscopic analysis of a biopsy of the wrist revealed structures in the form of short lobes with hollow interiors, surrounded by white blood cells. It seemed the typical reaction to the unauthorized incursion under the skin of a foreign agent. But which? The answer came by asking the patient about what he had done just before the appearance of the alleged eczema. Specifically five months ago.
Thinking back, he remembered that he got on a Apple tree of his patio and that at the top he found many sponge moth caterpillars (Lymantria dispar). It might be thought that she suffered an allergic reaction to exposure to her stinging hairs. But the situation was even more tense. And it is that she had not been exposed to the stinging hairsbut some of them had been under his skin for five months.
The moth that was renamed
In the apple tree, the protagonist of this story came into contact with a large number of caterpillars of fluffy moth.
It is a Eurasian moth, known until recently as gypsy moth. She changed her name to avoid falling into racism, by relating her to a specific ethnic group. But with one name or another, she is still a moth capable of causing great plagues.
In 2020, for example, it caused an uproar in Washington over a blight that left a large amount of the state’s forests nearly bare.
Possibly that is what was happening in this man’s yard. Moth caterpillars were infesting his apple tree and he decided to go up and see what was up. Once there he came into contact with some, but it didn’t occur to him that their hairs might have embedded in his skin. So when the eczema appeared on his wrist shortly after, she didn’t even notice the recent incursion of the caterpillar infestation on the apple tree in his yard.
The moral of confusing caterpillar hairs with eczema
Analysis of the biopsy concluded that after coming into contact with apple caterpillars some setae (hairs) they were embedded in his skin with enough depth so that it was not noticeable from the outside.
Given this situation, the treatment that had been used until now was changed. For this, they were administered 0.5 mL of betamethasone composed of 2 mg of betamethasone sodium phosphate and 5 mg of betamethasone dipropionatoin in 1 mL. The mixture was introduced into the lesion by intralesional injection once a month, for a period of 5 months. After all that time, the injury caused by the caterpillar completely disappeared.
The case has been reported in BMJ Case Reportsin a study in which its authors make an appeal to the diagnosis of this type of cases. Specifically, they appeal to health professionals who care for patients with Allergic dermatitisso that they take into account both occupational history and environmental exposure history. Thus, cases like that of this 50-year-old man could have been diagnosed much earlier, reducing the suffering of going from clinic to clinic, receiving different treatments for eczema that never really existed.