Purpose: We describe the clinico-pathologic and mammographic characteristics of inflammatory breast cancer (IBC) and non-IBC cases enrolled in a case-control study. Because IBC is a clinico-pathologic entity with rapid appearance of erythema and other signs, its diagnosis is based on clinical observation and thus, by necessity, subjective. Therefore, we evaluate our cases by photographic review by outside expert clinicians and by degree of adherence to the two most recent definitions of IBC: the international expert panel consensus statement and American Joint Committee on Cancer (AJCC) 8th edition (we used the slightly less restrictive 7th edition definition for our study).
Methods: We enrolled 267 IBC and 274 age- and geographically matched non-IBC cases at 6 sites in Egypt, Tunisia, and Morocco in a case-control study of IBC conducted between 2009 and 2015. We collected clinico-pathologic and mammographic data and standardized medical photographs of the breast.
Results: We identified many differences between IBC and non-IBC cases: 54.5% versus 68.8% were estrogen receptor-positive, 39.9% versus 14.8% human epidermal growth factor receptor 2-positive, 91% versus 4% exhibited erythema, 63% versus 97% had a mass, and 57% versus 10% had mammographic evidence of skin thickening. Seventy-six percent of IBC cases adhered to the expert panel consensus statement and 36% to the AJCC definition; 86 percent were confirmed as IBC by either photographic review or adherence to the consensus statement.
Conclusions: We successfully identified distinct groups of IBC and non-IBC cases. The reliability of IBC diagnosis would benefit from expert review of standardized medical photographs and associated clinical information.
Keywords: Diagnostic criteria; Egypt; Inflammatory breast cancer; Morocco; Tunisia.