Figure 1.

Clinical presentation and histopathological features of a patient with MALTA syndrome with BDSDP. (a) Clinical photograph (i) showing nodular erythematous swellings on the right infraorbital region (ii) and left zygomatic arch (iii), measuring approximately 2.5 and 3.2 cm in diameter, respectively. (b) H&E-stained tissue sections from the right infraorbital region at ×4 (i), with arrows indicating ducts exhibiting apocrine-like changes. H&E-stained tissue sections from the left zygomatic arch lesion at ×4 (ii) and ×10 (iii) reveal keratin horn cysts in the upper dermis, a feature mimicking MAC, along with myoid/collagenous stroma surrounding the cords and ductular proliferation, which are not typical of MAC. Arrows mark ducts with features of apocrine differentiation. Bar = 100 μm. (c) Immunohistochemical ancillary studies support apocrine differentiation: (i) p63 staining highlights the nuclei of the basal myoepithelial cell layer of the infiltrative ducts (×10); (ii) GCDFP-15 focally marks the luminal duct surface, a feature sometimes seen with apocrine differentiation (×10); (iii) EMA marks the luminal surface of the infiltrative glandular duct structures (×10); and (iv) CD15 positivity along the lumen surface and within the infiltrative ducts favors apocrine over eccrine origin (×10). Bar = 100 μm. The patient provided written informed consent for the use of his image in this publication. BDSDP, benign deep syringoid ductal proliferation; MAC, microcystic adnexal carcinoma.