PMC8586089_01
Skin manifestations and kidney histology of the patient. Photos show cystic acne before (A) and after (B) rechallenge of canakinumab. Histology analysis shows interstitial fibrosis with interstitial infiltration by mononuclear cells and tubular atrophy, classical and with aspects of thyroidization; tubular lumens are dilated and with flaking material; epithelium of some tubules appears vacuolated; segmental hyalinosis of arteriole is also present (C,D; periodic acid-Schiff staining; original magnification x 50 and x 200, respectively). Diffuse interstitial fibrosis (E,F; trichrome staining; original magnification at x 50 and x 200, respectively).
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F1
Since 8 years of age, severe pyoderma gangrenosum started at the periorbital and periungual area [refer to Figure 1B of reference ]. Tacrolimus (maintaining serum range of 4-6 ng/dl) was started, and canakinumab restarted due to worsening of the skin inflammatory manifestations (Figure 1A), resulting in a prompt clinical improvement of skin lesions (Figure 1B). One year later, due to the persistence of proteinuria in the nephrotic range (3.2 g/daily) with stable renal function (creatininemia 1.7 mg/dL, eGFR 56 ml/min/1.73 m2), a second kidney biopsy was performed in our center, showing interstitial fibrosis (Figures 1C-F).