PMC9792732_01
Clinical appearance of FGFR inhibitor-induced calcinosis cutis. A, Two images showing axillary metastatic calcinosis cutis. Pink, indurated plaque in the right axillae. B, Poorly circumscribed, circumferential sclerotic plaques of the legs with pitting edema of the lower extremities.
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A 62-year old male presented to the oncology clinic with complaints of new tender swelling and erythema beginning at the ankles and progressing superiorly to the thighs along with triangular areas of erythema on the bilateral axillae (Fig 1).
Timeline of clinical course. The timeline begins with the first pemigatinib dose and ends with follow-up computed tomography demonstrating resolution of calcinosis cutis with sodium thiosulfate therapy. CT, Computed tomography; STS, sodium thiosulfate.
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The patient was subsequently enrolled in a clinical trial evaluating the efficacy and safety of the FGFR tyrosine kinase inhibitor in previously treated metastatic or surgically unresectable solid tumor malignancies harboring FGFR mutations, pemigatinib (Fig 2).
Histopathological appearance of calcinosis cutis. Telescoping punch biopsy from left thigh demonstrating basophilic aggregates in the dermis and superior subcutaneous tissue septum (original magnification 40x). Higher magnification (inset, original magnification 100x) reveals uniformly basophilic deposits characteristic of calcium salts.
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Histopathology revealed deposition of basophilic calcium salts with surrounding granulomatous inflammation in the dermis (Fig 3).
Imaging of calcinosis cutis. A, Computed tomography (CT) imaging of the bilateral lower legs exhibiting prominent calcifications in the subcutaneous tissues, skin, and superficial fascial layers, before sodium thiosulfate therapy. Arrows highlight subcutaneous calcifications. B, CT of the lower legs demonstrating marked reduction in calcification of 90% in the subcutaneous tissues, skin, and superficial fascial layers, taken 4 months after starting sodium thiosulfate therapy.
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CT of the bilateral lower extremities demonstrated subcutaneous and superficial fascial calcifications in a linear pattern in the bilateral gluteal areas and thighs, right greater than left, with prominent calcifications seen in the lower legs (Fig 4). Four months after the patient began STS, a CT of the bilateral lower extremities demonstrated a reduction of over 90% in the subcutaneous and superficial fascial calcifications in the bilateral lower legs (Fig 4).