Picibanil is a freeze-dried (lyophilised) preparation of cultures of a low-virulence strand of streptococcus pyogenes bacteria. The initial stage of the preparation includes treatment of the culture with penicillin to kill the bacteria. Consequently, picibanil preparations are not a suitable medicinal drug for those who are allergic to penicillin.

Picibanil was first developed in Japan, some 40 years ago, in some early attempts to develop immunotherapies for the treatment of malignancies. Picibanil indeed acts as a non-specific stimulant of the immune system, including stimulation of the activity of natural killer cells, macrophages and lymphocytes. For example, it has been used as adjuvant (supportive) medication in conventional chemotherapy and its multiple interactions with the immune system continue to be researched. However, picibanil has never become an established immunotherapy drug in oncological treatments.

In addition to its immunostimulant properties, picibanil also acts as a sclerosing agent. This is its most significant use in maxillofacial surgery. It is an effective and selective agent in inducing the shrinkage of a certain type of cysts and the treatment is generally well tolerated. In this capacity, picibanil has become an established agent for the treatment of congenital lymphatic malformations, such as lymphangioma in the head and neck region (the most common location). Both surgical removal of these cystic lesions (the traditional first-line treatment) and sclerotherapy with picibanil have the best success in treating macrocystic (one large cyst) lesions, whereas the treatment of microcystic (multiple small cysts) lesions is more demanding surgically and has lower success rates with picibanil treatment. In the oral and maxillofacial region, picibanil sclerotherapy may sometimes be the preferable approach, when surgical interventions may lead to more severe functional and/or cosmetic deficiencies. Furthermore, initial picibanil treatment does not seem to have any adverse influence on subsequent surgical interventions.

Picibanil treatment typically involves needle aspiration of most of the fluid content from the cystic cavity and replacing it with picibanil solution injected into the lesion. There seems to be no standard procedure for the application of picibanil for this purpose, but this appears to be the most common method. Owing to its immunostimulant properties, picibanil typically triggers a swift, short-term local immune response in the form of tissue swelling. If the injected area is near the airway (for example, lesions located in the floor of the mouth or the oro-pharynx), precautions to protect the airway have to be kept in mind. It may also be argued that, if the airway is likely to be compromised, this would be an indication to secure the airway and to surgically remove the cyst.

Surgical removal of these lymphatic malformations and picibanil sclerotherapy have similar recurrence rates. Other sclerosing agents that are widely used in the treatment of, for example, varicose veins are not effective in the treatment of lymphangioma.