Woman with growing scalp mass

A 77-year-old woman presented to the emergency department with a growing lump on her scalp. The mass was present for a year and she was told it was benign; however, over the last few days, it had markedly increased. Examination revealed a tender, fluctuant mass but normal-appearing skin on the right parietal scalp, partially obscured by hair but appreciated on palpation. Point-of-care ultrasound (PoCUS) demonstrated a structure with mixed echogenicity extending through the skull and compressing what appeared to be brain gyri (Figures 1 and 2). Computed tomography (CT) confirmed that a large mass eroded through the scalp and exerted pressure on the brain parenchyma (Figures 3 and 4). Biopsy confirmed that the mass was diffuse large B-cell lymphoma (DLBCL). DLBCL is the most common subtype of non-Hodgkin lymphoma and often presents with erosive soft-tissue masses.1 Extra-nodal sites commonly include the gastrointestinal tract, head and neck, and extremities.2 Subcutaneous scalp lesions are rare and, as in this case, may be misdiagnosed as benign cystic structures.3 PoCUS is an essential diagnostic tool for emergency physicians with validated use in various clinical scenarios. Typical soft-tissue applications include identifying hypoechoic fluid collections concerning for abscess and tissues of other echogenicity, such as cysts or lymph nodes.4 In this case, PoCUS prompted advanced imaging and resulted in the diagnosis of an advanced-stage soft-tissue lesion with intracranial extension for a mass previously overlooked as benign. Direct application of PoCUS to the evaluation of brain tissue is a topic of interest and further research.5 The authors declare they have no conflicts of interest.