We present a 24-year-old female patient affected by neurofibromatosis type 1 (NF1) who developed a malignant phyllodes tumor of the breast. The molecular studies showed that the patient carried a heterozygous inactivating deleterious variant in BRCA1 inherited from the father associated with a germline de novo pathogenic alteration in NF1; the tumor presented a biallelic inactivation of both genes. Therefore, tumor analyses helped to establish that the germline NF1 and BRCA1 variants were in cis on the paternal chromosome. This last information is important to provide adequate genetic counselling regarding the risk of recurrence in the offspring, as well as opportunity for early intervention. In conclusion, we present the first case of a malignant phyllodes tumor of the breast in patient carrying pathogenic variants in NF1 and BRCA1. Further studies will be necessary to understand if the phyllodes histotype represents a very rare component of NF1-associated breast cancer.

我们介绍了一名受 1 型神经纤维瘤病 (NF1) 影响的 24 岁女性患者，她患有乳腺恶性叶状肿瘤。分子研究表明，患者携带杂合子失活的有害变异BRCA1从与生殖有关的父亲那里继承从头致病性变化在NF1; 肿瘤表现出两个基因的双等位基因失活。因此，肿瘤分析有助于确定生殖系NF1和BRCA1变体是顺式在父系染色体上。最后的信息对于提供关于后代复发风险的充分遗传咨询以及早期干预的机会很重要。总之，我们介绍了第一例携带NF1和BRCA1致病变异的患者的乳腺恶性叶状肿瘤。需要进一步研究以了解叶状组织型是否代表 NF1 相关乳腺癌的一种非常罕见的成分。