Fibrous Hamartoma of Infancy: A Firm Plaque Presenting with Hypertrichosis and Hyperhidrosis

Fibrous hamartoma of infancy with bone destruction of the tibia: A case report

BACKGROUND

Fibrous hamartoma of infancy (FHI) is a rare disease of infancy with unknown etiology. The disease mainly involves soft tissue, has no specific clinical manifestations, and is difficult to diagnose. At present, the diagnosis is mainly confirmed by histopathological examination, and the main treatment is surgical resection of the pathological tissue, which is prone to recurrence.

CASE SUMMARY

A five-month-old female patient was admitted to our hospital with swelling in the right calf. Two biopsies were performed in our hospital and another hospital, respectively, confirming the diagnosis as fibrous hamartoma. After exclusion of surgical contraindications, resection was performed with clear margins of 1 cm. Radiographic examination showed tumor recurrence more than four months after the operation, and surgery was performed again to extend the resection margins to 1.5 cm. The patient is recovering well, and after a follow-up of 36 mo, shows no signs of recurrence.

CONCLUSION

Our case report demonstrates that FHI should be considered in the differential diagnosis for a lower extremity mass with bone destruction. For FHI with bone destruction and unclear boundaries, excision margins of 1.5 cm could be superior to margins of 1 cm.

Fibrous Hamartoma of Infancy: A Series of 21 Cases and Review of the Literature

BACKGROUND

Fibrous hamartoma of infancy (FHI) is a rare soft-tissue tumor usually seen in infants and young children. Histologically, the tumor is characterized by a triphasic morphology, and the clinical course is benign.

METHODS

We described the histopathologic and immunohistochemical features in a series of 21 cases of FHI and reviewed the main entities to consider in differential diagnosis.

RESULTS

Most patients in the series were male. The mean age was 3.7 years (range, 5 months-24 years), and lesions were found in locations that have been previously reported. Histopathologically, the tumors were composed of variable proportions of fibroblastic, mesenchymal, and mature adipose tissue. Three of the 13 immunohistochemically stained biopsies (14%) contained hyalinized zones with cracking artifacts, mimicking giant cell fibroblastoma. Eight of the 13 stained with smooth-muscle actin (61%) were positive in the fibroblastic component, 6 of the 8 stained with CD34 (75%) were positive in the immature mesenchymal and fibroblastic components, and all 7 stained with S100 were positive (100%) in adipose tissue.

CONCLUSIONS

Our histopathologic findings are consistent with those described in larger series. However, in order to reach a precise diagnosis and plan treatment, clinical heterogeneity obliges us to become familiar with variations in the characteristic triphasic histology of FHI.

Nonepithelial Tumors and Tumor-like Lesions of the Skin and Subcutis in Children

This overview of mesenchymal tumors presenting in the skin and/or subcutis in children brings together the range of neoplasms and hamartomas which are seen in this age-group. It is not surprising from the perspective of the pediatric or general surgical pathologist that vascular anomalies, including true neoplasms and vascular malformations, are the common phenotypic category. Since there is considerable morphologic overlap among these lesions, clinicopathologic correlation may be more important than for many of the other mesenchymal tumors. The skin and subcutis are the most common sites of clinical presentation for the infantile myofibroma which is the most common of fibrous mesenchymal tumors in children. Several of the other mesenchymal tumors are more common adults-like dermatofibrosarcoma protuberans, but nonetheless have an important presence in children, even as a congenital neoplasm. A lipomatous tumor in a young child should be considered as a possible manifestation of an overgrowth syndrome.

The First Reported Case of Fibrous Hamartoma of Infancy with Hyperhidrosis and Hypertrichosis in Korea

Fibrous hamartoma of infancy (FHI) is a rare entity with a benign nature. The typical clinical features are a single, slowly growing, painless mass on the trunk that appears within the first 2 years of life. We report a 13-month-old boy who presented with a plaque on the lower back since 4 months of age. The plaque had gradually become larger and firm, and hyperhidrosis and hypertrichosis were noticed. No visible connection between the spinal cord and the lesion was found in radiologic studies, indicating a disease other than spinal dysraphism. Histopathological findings showed well-defined fibrous trabeculae, mature adipose tissue, and primitive mesenchymal cells, all consistent with FHI. This is the first case of FHI presenting with hyperhidrosis and hypertrichosis reported in Korea.

Fibrous hamartoma of infancy: a clinicopathologic study of 145 cases, including 2 with sarcomatous features

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.