From mass to epidermolysis: a rare case of multiple metastatic solitary fibrous tumor with paraneoplastic pemphigus

Abstract

due to a 1-month history of severe epidermolysis (Figure 1a). Of note, she had been diagnosed with systemic lupus erythematosus (SLE) in 2012 due to arthralgia, elevated levels of double-stranded DNA (dsDNA >800 IU) and antinuclear antibody titer (ANA >1 : 320). Oral methylprednisolone and cyclophosphamide (CTX) were given. Further examination revealed a large abdominal mass with benign pathology (17 cm x 10 cm, SUV = 2.9). Surgery was not performed after weighing the risks of surgery against the rather benign biological behavior of the tumor.However, in February 2020, she developed a highly vascular extra-axial tumor. The postoperative pathology of the cranial lesion confirmed the diagnosis of solitary fibrous tumor (SFT). Two months later, she suffered full-body blistering and epidermolysis (Nikolsky's sign positive), severe oral and genital erosions, and fever.Laboratory tests showed elevated anti-desmoglein (Dsg) 1 (161.8 IU/ml), Dsg3 (110.2 IU/ml), and positive envoplakin, while anti-bullous pemphigoid (BP) 180 and BP 230 were negative. Indirect immunofluorescence (IIF) on rat bladder (Figure 1c) showed a weak positive result of scattered intracellular staining. Skin tissue pathology demonstrated acantholysis above the basal layer (Figure 1d). All of the above features strongly supported a diagnosis of paraneoplastic pemphigus (PNP). After 2 months of tailored treatment with glucocorticoids (GC) and other supportive *The first two authors contributed equally to this work.