Based on the history and the examination findings, a diagnosis of non-infectious superficial lymphangitis induced by arthropod bite was made. Treatment with medium potency topical corticosteroids and oral antihistamines was started, achieving a complete response within four days. Non-infectious superficial lymphangitis after an insect bite is an uncommon variant of acute lymphangitis without fever or lymphadenopathy, unlike classical streptococcal forms.1,2
It has been hypothesised that it is caused by an allergic reaction to toxins injected, with no evidence of local infection.1 The toxins are drained by lymphatic vessels towards local lymph nodes, determining a linear inflammatory response in the overlying skin.1,3 Certain subsets of patients, like those with haematological diseases, are prone to developing greater reactions to insect bites, including lymphangitic streaking.2
In order to exclude bacterial lymphangitis, an accurate differential diagnosis should be made that could benefit from an antibiotic course to avoid further complications. Other entities that may cause similar skin lesions include phytophotodermatitis, lymphatic filariasis, Mondor’s disease, or superficial migratory thrombophlebitis. Although non-complicated superficial lymphangitis resolves spontaneously after a few days as the hypersensitivity reaction diminishes, treatment with topical corticosteroids and oral antihistamines may improve the patient’s symptoms.
In this case, the casual fact that the arthropod bite occurred in the umbilicus resulted in two different streaks, perfectly representing lymphatic drainage from central abdomen to both axillary and groin nodes in left and right sides, leading to a bizarre and unique clinical image.4
All authors declare no conflicts of interest. No funding or financial support was received.