前情提要
诊断：特发性肉芽肿性乳腺炎
特发性肉芽肿性乳腺炎是罕见的乳腺慢性炎性疾病，临床和影像表现与乳腺癌相似，病因不明【1】。可能病因包括微生物、自身免疫、吸烟、激素失衡、妊娠、分娩、哺乳、α1-抗胰蛋白酶缺乏症、异物反应。通常表现为与皮肤炎症相关的单侧、坚硬、疼痛的乳房肿块，无全身疾病表现。也可能发生淋巴结肿大，如该患者【2,3】。
乳腺钼靶无特异性发现，如该患者。通常表现为单侧局灶不对称、结构扭曲或不规则肿块。此外，由于大多患者较年轻，故高密度纤维腺通常可掩盖病变检出。
超声检查通常显示低回声肿块，边缘不规则、不清晰、不光滑，与癌症相似【2】。该患者导管周围囊肿相关乳腺组织弥漫性低回声与导管周围乳腺炎伴导管周围肉芽肿的病理学表现相似。
根据组织学分析，小叶周围非坏死性肉芽肿与由多核巨细胞、浆细胞、上皮样组织细胞、淋巴细胞构成的炎性浸润有相关性（图2）。
图2、组织学分析。乳腺小叶被肉芽肿炎症包围并破坏；肉芽肿由上皮样组织细胞、淋巴细胞、浆细胞、嗜酸性粒细胞构成。
临床鉴别诊断应首先排除年轻个体的炎性乳腺癌和感染性乳腺炎或免疫抑制性乳腺炎。年轻人的乳腺癌发病率较低，该患者无乳腺癌或卵巢癌家族史，但是可能有罕见的妊娠相关乳腺癌。
对于此类患者，必须进行组织学分析。该患者乳房上方和腋窝的活检标本组织学分析排除了癌症。多学科评估认为超声引导活检结果足以确诊，并确定手术切除活检无必要。由于瘢痕，手术活检显著影响乳房美观。
此外，患者近期有严重肺炎，自行服用普通抗生素治疗。结核性乳腺炎也应考虑。血液检查有助于正确诊断，并可排除开始免疫抑制治疗之前免疫抑制所致乳腺炎。该患者全血γ干扰素释放试验结果为阴性，可排除结核病，而人免疫缺陷病毒检测结果阴性可排除了其他可能原因所致免疫抑制。
治疗：抗生素通常无效。近20年来，保守治疗（随访，皮质类固醇治疗或免疫调节剂治疗）得到普及。目前仅对无效者建议手术。该病例病情为自限性，2个月后无任何治疗即临床缓解，5个月后完全缓解。
JAMA Surg. 2017 Jul 12. [Epub ahead of print]
A Young Woman With a New Breast Mass.
Iacconi C, Vatteroni G, Ginori A.
Aziende USL Toscana Nord Ovest, Carrara, Italy; University of Pisa, Pisa, Italy.
Diagnosis: C. Idiopathic granulomatous mastitis
Idiopathic granulomatous mastitis (IGM) is a rare chronic inflammatory disease of the breast that can clinically and radiologically mimic breast carcinoma. It is a rare disease with an unknown origin.[1] Various factors, such as microbiological agents, autoimmunity, smoking, hormonal imbalance, gestation, birth and breastfeeding, α1-antitrypsin deficiency, and foreign-body reaction, have been considered as possible causes of the disease. It usually presents as a unilateral, hard, painful breast mass associated with inflammation of the skin, without signs of systemic disease. Enlarged lymph nodes may also occur, as observed in this patient.[2,3]
At mammography, IGM has nonspecific findings, as also seen in this patient. It usually appears as unilateral focal asymmetry, architectural distortion, or an irregular mass. Furthermore, because of the young age of most affected patients, high fibroglandular density usually can mask lesion detection.
Ultrasonography often reveals a hypoechoic mass with irregular, indistinct, and angular margins, mimicking cancer or diffuse hypoecogenicity.[2] In this patient, the diffuse hypoecogenicity of the breast tissue associated with microcysts close to the ducts resembled the pathologic findings of periductal mastitis with small periductal granuloma.
At histologic analysis, nonnecrotizing granulomas around the lobules are associated with inflammatory infiltrates composed of multinucleated giant cells, plasma cells, epithelioid histiocytes, and lymphocytes (Figure 2).
Figure 2. Histologic analysis. The lobules of the breast were surrounded and destroyed by granulomatous inflammation; the granulomas were composed of epithelioid histiocytes accompanied by lymphocytes, plasma cells, and eosinophils.
The clinical differential diagnosis should be performed initially with breast cancer mastitis in young individuals and with infective mastitis or mastitis caused by immunosuppression. The incidence of breast cancer in young individuals is sporadic, and this patient had no family history of breast or ovarian cancer, but she could have had a rare pregnancy-associated breast cancer.
Histologic analysis is mandatory in this type of patient. In this patient, histologic analysis of several biopsy specimens of the upper quadrant of the breast and in the axilla excluded cancer. Multidisciplinary evaluation considered the results of ultrasound-guided biopsy to be adequate and determined that excisional biopsy was not necessary for diagnosis. Surgical biopsy would have had a significant effect on the aesthetic outcome of the breast because of the scar.
Furthermore, the patient recently had severe pneumonia, which she self-medicated with a generic antibiotic treatment. Tuberculous mastitis also should be taken into account. Blood tests are necessary for a correct diagnosis and to exclude mastitis caused by immunosuppression before starting immunosuppressive therapy. A negative whole-blood interferon γ release assay test result in this patient excluded tuberculosis, and a negative human immunodeficiency virus test result excluded other possible causes of immunosuppression.
In the treatment of IGM, general antibiotics are often used without success. Conservative treatment (follow-up, corticosteroid therapy, or treatment with immunomodulators) has gained popularity in the past 20 years. Surgery is currently suggested only for nonresponders. This case was a self-limiting condition, and clinical improvement occurred without any therapy after 2 months. Complete resolution was observed after 5 months.
参考文献
Sripathi S, Ayachit A, Bala A, Kadavigere R, Kumar S. Idiopathic granulomatous mastitis: a diagnostic dilemma for the breast radiologist. Insights Imaging. 2016;7(4):523-529.
Seo HRN, Na KY, Yim HE, et al. Differential diagnosis in idiopathic granulomatous mastitis and tuberculous mastitis. J Breast Cancer. 2012;15(1):111-118.
Benson JR, Dumitru D. Idiopathic granulomatous mastitis: presentation, investigation and management. Future Oncol. 2016;12(11):1381-1394.
PMID: 28700787
DOI: 10.1001/jamasurg.2017.2172
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