[Local Allergic Reaction to Subcutaneous Treatment with Procaine in a Patient with Shoulder Pain - a Case Study].

HISTORY: A 53-year-old man presented at the general practitioner's office with 2 weeks of existing shoulder pain without radiation. On physical examination, no abnormalities were found, except for left-sided tension of the shoulder muscles.

FINDINGS AND DIAGNOSIS: Because of the expected self-limiting nature of the complaints, no further tests were conducted. Based on shoulder pain with local muscle tension, the working diagnosis cervicobrachialgia was adopted.

THERAPY AND COURSE: The pain was treated with local subcutaneous administration of procaine. 4 days later, the patient presented with distinct patches of urticaria at the injection sites, which regressed spontaneously over the course of 2 weeks.

DISCUSSION: Allergic reactions occuring after treatment with procaine are rare, but can be life-threatening if systemic or afflicting vital structures.Patients should be informed about the importance of the allergy in relation to medical procedures, such as dental treatment, and about cross-reactivity with other medication.