Al-Ibraheemi Alyaa, Martinez Anthony, Weiss Sharon W, Kozakewich Harry P, Perez-Atayde Antonio R, Tran Henry, Parham David M, Sukov William R, Fritchie Karen J, Folpe Andrew L
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
Department of Laboratory Medicine and Pathology, Emory University, Atlanta, GA, USA.
Mod Pathol. 2017 Apr;30(4):474-485. doi: 10.1038/modpathol.2016.215. Epub 2017 Jan 6.
Fibrous hamartoma of infancy is a rare soft tissue lesion of infants and young children with characteristic triphasic morphology, which typically occurs in the axilla and less commonly in other locations. We reviewed 145 cases of fibrous hamartoma of infancy from our consultation archives. Cases occurred in 106 males and 39 females (mean age-15 months; range-birth to 14 years), and involved both typical sites (eg, axilla/back/upper arm) (n=69) and unusual locations (n=76). Six were congenital. The tumors presented as subcutaneous masses and ranged from 0.4 to 17 cm (mean 3 cm). All displayed triphasic morphology, but varied widely in the relative percentages of fat, fibroblastic fascicles, and primitive mesenchyme. Hyalinized zones with cracking artifact, mimicking giant cell fibroblastoma, were present in a 44 (30%) of cases; however FISH for PDGFB gene rearrangement was negative in five tested cases. In addition to classical fibrous hamartoma of infancy, two lesions contained large sarcomatous-appearing foci with high cellularity, high nuclear grade, and brisk mitotic activity. One occurred in a 10-month-old female as a new mass in a congenital fibrous hamartoma of infancy; the other occurred as a leg mass in a 6-year-old male. ETV6 gene rearrangement was negative in the tumor from the 10-month-old female. Genomic microarray (OncoScan) showed normal molecular karyotype in eight tested cases, whereas the two tumors with sarcomatous features showed a hyperdiploid/near tetraploid molecular karyotype with copy neutral loss of heterozygosity of chromosomes 1p and 11p, and loss of 10p, chromosome 14, and a large portion of chromosome 22q (22q11.23q13.33), respectively. Follow-up (52 patients; range: 1-208 months, median: 8 months) showed only two local recurrences and no metastases. Extensive local disease in the 10-month-old female with sarcomatous-appearing fibrous hamartoma of infancy necessitated forequarter amputation. In summary, our study confirms the classic clinicopathologic features, including the triphasic morphologic appearance of most cases. In contrast to earlier studies, our series illustrates a broader histologic spectrum than previously appreciated, including its close resemblance to giant cell fibroblastoma in one quarter of cases and the rare presence of 'sarcomatous' areas, the latter providing evidence that these are complex neoplasms rather than hamartomas.
婴儿纤维性错构瘤是婴幼儿罕见的软组织病变，具有特征性的三相形态，通常发生于腋窝，较少见于其他部位。我们回顾了会诊档案中的145例婴儿纤维性错构瘤病例。病例发生于106例男性和39例女性（平均年龄15个月；范围从出生至14岁），累及典型部位（如腋窝/背部/上臂）（n = 69）和非典型部位（n = 76）。6例为先天性。肿瘤表现为皮下肿块，大小从0.4至17 cm（平均3 cm）。所有病例均显示三相形态，但脂肪、成纤维细胞束和原始间充质的相对比例差异很大。44例（30%）病例中存在伴有裂隙伪像的玻璃样变区域，类似巨细胞纤维母细胞瘤；然而，5例检测病例的PDGFB基因重排荧光原位杂交结果为阴性。除了经典的婴儿纤维性错构瘤外，2例病变含有大的肉瘤样病灶，细胞丰富、核级别高且有活跃的核分裂象。1例发生于10个月大的女性，是先天性婴儿纤维性错构瘤中的新肿块；另1例发生于6岁男性的腿部。10个月大女性肿瘤中的ETV6基因重排为阴性。基因组微阵列（OncoScan）显示8例检测病例的分子核型正常，而2例具有肉瘤特征的肿瘤分别显示超二倍体/近四倍体分子核型，伴有1p和11p染色体杂合性的拷贝中性缺失，以及10p、14号染色体和22号染色体大部分（22q11.23q13.33）缺失。随访（52例患者；范围：1 - 208个月，中位数：8个月）显示仅2例局部复发，无转移。10个月大患有婴儿肉瘤样纤维性错构瘤的女性广泛的局部病变需要进行上肢截肢。总之，我们的研究证实了经典的临床病理特征，包括大多数病例的三相形态外观。与早期研究不同，我们的系列病例显示出比以往认识更广泛的组织学谱，包括四分之一病例与巨细胞纤维母细胞瘤密切相似，以及罕见的“肉瘤样”区域，后者证明这些是复杂的肿瘤而非错构瘤。
