Interstitial dermal infiltrate: an intriguing pattern

Loss of CD34 Expression within an Interstitial Dermal Lymphoid Cell Infiltrate Is a Helpful Clue to the Diagnosis of Morphea

“…The differential diagnosis of lymphocyte-predominant interstitial inflammatory cell infiltrate is broad and varies from Schamberg’s disease to interstitial mycosis fungoides (IMF) [ 3 ]. Indeed, distinguishing early morphea from these disorders can be quite difficult [ 3 ].…”

“…In this setting, loss of CD34 expression and plasma cells in the infiltrate point towards the diagnosis of morphea [ 3 ]. In a recent study, plasma cells were always found in morphea specimens even when collagen homogenization was absent [ 1 ].…”

“…In Schamberg’s disease, extravasation of erythrocytes and hemosiderin deposition are helpful findings [ 3 ]. Early erythema migrans may have similar features to morphea, with a perivascular and interstitial superficial and deep lymphoplasmacytic cell infiltrate; however, frequent extension of the infiltrate in the subcutaneous fat is typically present.…”

“…Early erythema migrans may have similar features to morphea, with a perivascular and interstitial superficial and deep lymphoplasmacytic cell infiltrate; however, frequent extension of the infiltrate in the subcutaneous fat is typically present. Neutrophils and eosinophils may also be seen [ 3 ]. As for IMF, the presence of lymphocytic atypia is the main differentiating feature, and the lymphocytes are usually of the cytotoxic CD8+ phenotype [ 9 , 10 ].…”

“…However, the diagnosis of morphea histologically can be challenging, particularly in the early inflammatory stage when it might lack the characteristic stromal changes and manifest with a non-specific perivascular and interstitial lymphocytic cell infiltrate. Accordingly, about half of the biopsies may be non-diagnostic [ 1 , 3 ]. In addition, distinguishing inflammatory morphea from the late inactive stage is difficult both clinically and histologically [ 1 ].…”