Fig. 1
Overview of the case, including targeted response of a metastatic MPTT to PI3K inhibition. a Timeline of the patient’s course of disease starting with her neck dissection at a tertiary care center. Note: as detailed in the text, the patient had a recurrent posterior scalp lesion treated with local excisions for many (10+) years prior to her neck dissection. b Hematoxylin and eosin (H&E) stain of original diagnostic biopsy (4Ă—). Note: (1) the dermal proliferation of convoluted lobules that infiltrate the deep dermis and subcutis, with tricholemmal type keratinization typical of PTT (dashed ellipse); and, (2) in the deeper sheets of cells there is cytologic atypia, increased mitoses, and infiltrating margins diagnostic for MPTT (dashed box). c CT scans of patient demonstrating radiographic response of MPTT to BYL719 (alpelisib). Left images = patient after six cycles of chemotherapy (largest paratracheal mass diameter = 13 mm; largest subcarinal mass diameter = 19 mm); right images = patient after 3 months of treatment with alpelisib (largest paratracheal mass diameter = 4 mm; largest subcarinal mass diameter = 9 mm). LN = lymph node. d Molecular response of MPTT to alpelisib. H&E and Ki67 (a marker of cellular proliferation) of tumor tissue before alpelisib treatment (top) and after 3 months of alpelisib treatment (middle). Nearby healthy skin (bottom) was also biopsied 3 months after initiation of alpelisib treatment and demonstrates normal proliferation of stratum basale. e) Quantification of tumoral Ki67 positive nuclei before and during treatment with alpelisib. Data are presented as mean ± standard deviations (n = 3 separate sections of ≥100 nuclei). **p = 0.0036 by unpaired t-test
