PMC8720602_01
(a) MRI of the right breast with IV gadolinium shows an oval enhancing mass in the upper inner right breast middle depth; (b) T2-weighted images show bright signal, though less bright than cysts seen elsewhere in the breast. Slit-like spaces are not definitely appreciated, possibly due to the small size of the finding. (c) Second-look ultrasound shows an oval, microlobulated, hypoechoic mass in the upper inner right breast, corresponding with that seen on MRI.
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The right breast ultrasound showed a 0.8 x 0.7 x 0.6 cm oval circumscribed mass which corresponded with that seen in MRI (Figure 1).
Low-power histologic assessment shows scattered nonneoplastic breast epithelial elements including scattered ducts and the edge of a terminal duct lobular unit with stromal expansion between and within these epithelial structures. Eosinophilic expanses of fibrous tissue are noted with linear arrangements of spindle cell nuclei resulting in a tiger-stripe-like pattern ((a) hematoxylin and eosin, 100X). At intermediate magnification, the nuclear arrangements with offset eosinophilic cytoplasmic bands emphasize the striped morphology ((b) hematoxylin and eosin, 200X).
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The cells were cytologically bland with no significant nuclear atypia or pleomorphism (Figure 2). The combined histomorphology and IHC results confirmed a cellular variant of PASH with a unique "tiger-striped" or "zippered" morphology (Figures 2-3).
High-power histologic assessment confirming a zippered morphology with interlacing lesional nuclei oriented perpendicular to the cleft space ((a) hematoxylin and eosin, 400X). The lesional spindled cells demonstrate diffuse and strong immunoreactivity with CD34 while the adjacent epithelium is nonreactive ((b) CD34 IHC, 600X). The lesional spindled cells also show immunoreactivity with progesterone receptor ((c) PR IHC, 600X).
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These confirmed the spindled cells to be immunoreactive with CD34 (diffusely strongly positive), SMA (diffusely moderatley positive), PR (variably moderately positive), ER (focally weakly positive), and RB (no loss of RB) (Figure 3). The combined histomorphology and IHC results confirmed a cellular variant of PASH with a unique "tiger-striped" or "zippered" morphology (Figures 2-3).