Shoulder Pseudo-Tumor from COVID-19 Vaccine

Abstract

Hypersensitivity reactions to the COVID-19 mRNA vaccines were identified in the initial 2020 trials. Appearance of a soft tissue mass is a rare manifestation of this hypersensitivity reaction. In this patient, bilateral injections resulted in the appearance of shoulder masses. Magnetic resonance imaging showed localized pseudo-tumorous edema in both shoulders, one subcutaneous and the other intramuscular. This is only the second case of a mass-like reaction to the COVID-19 vaccine mimicking a possible soft tissue neoplasm. Improper vaccination administration technique may have contributed to this complication. The case is presented to increase awareness of this potential pseudotumor.

Keywords: COVID-19; SARS-CoV-2; SIRVA; edema; education; orthopedics; shoulder; tumor; vaccine.

Figure 1

Multiplanar MRI of right shoulder taken 8 months after vaccine administration in right shoulder. Axial T2 (A) and coronal T2 (B) images show ill-defined fluid signal surrounding interspersed areas of fat. The involved area extended from surgical neck of the humerus to distal diaphysis, measuring approximately 14.9 × 8.2 × 1.8 cm (arrows).

Figure 2

Multiplanar MRI of left shoulder taken 10 months after vaccine administration in left shoulder. Axial T1 weighted (A) image shows predominately intramuscular edema within the lateral deltoid muscle measuring 5.6 cm anterior-posterior and 1.0 cm medial-lateral (arrows). Coronal T1 weighted (B) image shows intramuscular edema within the lateral deltoid muscle measuring 10.0 cm proximal-distal (arrows). Axial T2 STIR (C) and coronal T1 weighted (D) images show a slightly enlarged left axillary node (9.9 × 11.2 × 12.8 mm) (arrows).