Background: Primary cutaneous B-cell lymphoma and B-cell pseudolymphoma may show similar clinical and microscopic presentations, and sometimes represent a real diagnostic challenge for both clinician and pathologist.
Observation: A 64-years-old woman with a three months history of multiple, firm, reddish, pruritic and excoriated papules and nodules extensively distributed on the back and on her legs. The patient was otherwise healthy, with a medical history of back pain and fibromyalgia. Histopathologic examination showed a prominent dermal nodular lymphoid infiltrate with germinal centers surrounded by a dense infiltrate composed of small round lymphocytes, histiocytes, mature plasma cells, and eosinophils. Most of the cells in the infiltrate were positive for the pan-B cell marker CD20. The cells in the germinal centers were also positive for CD10, BCL6, and BCL2. The small lymphocytes in the infiltrate were positive for CD3. Moreover, CD5, CD19, CD23, and CD68 were found to be positive. Patient history revealed that 3 and 6 weeks prior to the onset of the skin eruption, she had undergone a course of natural therapy for back pain and chronic fibromyalgia that involved applying medical leeches. Therefore, a favored diagnosis of pseudolymphoma secondary to the application of leeches was made. Topical and intralesional steroid therapy resulted in a complete resolution. The term pseudolymphoma designates a group of reactive lymphocytic disorders that involve an inflammatory response to known or unknown stimuli simulating malignant lymphomas both clinically and histologically.
Key message: Medicinal leeches have historically been used as a non-conventional treatment for chronic venous insufficiency. In addition, less common applications such as osteoarthritis, muscular pains, or injuries have been reported. With the increasing popularity of traditional and alternative medicine, H. medicinal therapy is becoming increasingly popular. In conclusion, we all have to be aware that pseudolymphoma represents a possible complication in this type of treatment.