Arnam, John S. Van

Introduction: Solitary fibrous tumor (SFT) is a fibroblastic tumor with malignant potential that is underpinned by a recurrent inv12(q13q13)-derived NAB2::STAT6 fusion. Breast and axilla are uncommon locations for this entity. Methods: Records of two academic institutions were electronically searched for breast and axillary SFTs. Clinical and pathologic data were reviewed. Literature review for breast or axillary SFTs was performed. Present study and previously reported tumors were stratified using five SFT risk models: original and modified Demicco metastatic risk, Salas local recurrence risk, Salas metastatic risk, and Thompson local recurrence risk. Results: Five patients with breast or axillary SFT were identified. Median age was 49 years, and median follow-up (available for four patients) was 82 months. Three patients showed no evidence of disease, and one developed recurrence. Literature review identified 58 patients with breast or axillary SFT. Median age was 54 years, and median follow-up (available for 35 patients) was 24 months. Thirty-one patients showed no evidence of disease, three developed recurrence, and one developed metastasis. Original and modified Demicco models and Thompson model showed the highest sensitivity; original and modified Demicco models and Salas metastatic risk model demonstrated the highest specificity. Kaplan–Meier models were used to assess recurrence-free probability (RFP). Original and modified Demicco models predicted RFP when stratified by “low risk” and “moderate/intermediate and high risk” tumor, though sample size was small. Conclusions: While many SFTs of breast and axilla remain indolent, a subset may develop recurrence and rarely metastasize. The modified Demicco risk model demonstrated optimal performance characteristics.

Liver biopsies obtained for abnormal liver enzymes or unexplained ascites occasionally appear histologically almost normal. The differential diagnosis for these cases is challenging because literature addressing this topic is lacking. We aimed to establish a differential diagnosis and determine clinical associations and outcomes for almost-normal liver biopsies. Ninety-seven histologically almost-normal liver biopsies were collected from 2 institutions. All cases lacked significant inflammation, fatty change, biliary tract disease, vascular disease, nodular regenerative hyperplasia, iron overload, inherited metabolic or storage disorder, viral hepatitis, or fibrosis. Biopsies for follow-up of known liver diseases were excluded. Transplant biopsies, lesion-directed biopsies, biopsies obtained during bariatric surgery, liver donor biopsies, and biopsies to evaluate methotrexate toxicity were excluded. Clinical (including follow-up) and laboratory data were collected. The frequency of almost-normal liver biopsies was 0.6% and 3.7% at the 2 institutions. The most common biopsy indications were elevated liver biochemistries or clinical findings that suggested portal hypertension. In 70 patients (72%), an associated clinical abnormality was identified; the most common were autoimmune systemic inflammatory conditions (18%), vascular/ischemic events (13%), metabolic syndrome (11%), drug effects (8%), and inflammatory conditions of the gastrointestinal tract (7%). The median follow-up period was 4.3 years (range=0 to 10 y); detailed clinical follow-up was available for 66 patients (68%). Liver biochemistries normalized in 32 patients (48.5%) and remained elevated in 34 (51.5%). Seven patients (7.2%) eventually developed chronic liver disease (autoimmune hepatitis [n=3], primary biliary cirrhosis [n=3], cryptogenic cirrhosis [n=1]). This multicenter study determines the differential diagnosis for almost-normal liver biopsies; this will guide pathologists in subsequent workup efforts in these challenging cases.