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Year : 2019  |  Volume : 62  |  Issue : 3  |  Page : 509-510
Fibrous hamartoma of infancy with pseuodoangiomatous pattern

Department of Pathology, M.L.N. Medical College, Allahabad, Uttar Pradesh, India

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Date of Web Publication26-Jul-2019

How to cite this article:
Singh A, Singh P, Bhatt M, Misra V. Fibrous hamartoma of infancy with pseuodoangiomatous pattern. Indian J Pathol Microbiol 2019;62:509-10

How to cite this URL:
Singh A, Singh P, Bhatt M, Misra V. Fibrous hamartoma of infancy with pseuodoangiomatous pattern. Indian J Pathol Microbiol [serial online] 2019 [cited 2021 Jun 13];62:509-10. Available from: https://www.ijpmonline.org/text.asp?2019/62/3/509/263471


Fibrous Hamartoma of Infancy (FHI) is a very rare tumor of childhood. Most of the cases come to notice by second year of life, though some have been reported in later period as well. It shows a strong predilection for male sex and for acral areas of the body with a very characteristic triphasic organoid architecture of adipose tissue, fibroblastic tissue and immature mesenchymal tissue in variable proportions.[1] We present here a case of FHI presenting in an eight year old male child with a variant morphology of dominant pseudoangiomatous pattern which has been reported in very few cases in the literature till date.[2],[3]

An eight year old male child presented with a slowly progressive, non-tender right axillary mass that was noticed by the parents a few months after birth. Grossly, it was a single globular piece of tissue measuring 5 × 4 × 2.5 cm in size and the cut surface was homogenous white. Sections examined from the mass showed keratinized stratified squamous epithelium lined tissue showing an encapsulated triphasic organoid architecture pattern composed of mature adipocytes, intersecting fascicles of fibroblastic spindle cells and predominant collagenised areas showing prominent psuedoangiomatous pattern with occasional foci of immature mesenchymal tissue. No atypia, mitosis or necrosis was noted. On IHC, the adipocytes were S100 positive, and CD34 highlighted the psuedoangiomatous pattern the immature mesenchymal tissue was SMA negative. Based on histopathological and IHC findings, the case was diagnosed as fibrous hamartoma of infancy [Figure 1].
Figure 1: (a) Gross showing a well encapsulated mass measuring 5 × 4 × 2.5 cm. (b) Cut surface of the mass is homogenous white. (c) Section showing triphasic pattern composed of mature adipocytes (*), intersecting fascicles of fibroblastic spindle cells (arrow head) and collagenised areas showing prominent psuedoangiomatous pattern (arrow) (40×, H and E). (d) Section showing the collagenised areas with pseudoangiomatous pattern (100×, H and E). (e) Same area in higher magnification (400×, H and E). (f) Psuedoangiomatous spaces positive for CD 34 (400×, IHC)

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FHI is a rare tumor with a 0.02% frequency relative to all benign soft-tissue tumors. The disease was first described by Reye in 1956 as a subdermal fibromatous tumor of infancy and was re-named as fibrous hamartoma of infancy in 1965 by Enzinger.[4] The majority of cases occur within the first two years of life, out of which approximately one fifth are congenital. There is a predilection for boys with a male/female ratio of 2.4:1.[5] They occur mainly on the armpits, scapula and upper arm followed by the thigh, groin, buttocks, back, forearms, scrotum and the head/face. When FHI onset is at an older age, lesions are more common in the hands and feet. Almost all FHI tumors are solitary painless nodules located in the deep dermis or subcutis.[4]

Though it is named as a hamartoma, some researchers believe that FHI should be regarded as a tumor owing to its congenital appearance in many, rare reports of coexistent sarcomatoid areas,[3] few cases of associations with tuberous sclerosis or Williams syndrome[5] and the various cytogenetic alterations reported in the recent past.[2]

All cases show the characteristic triphasic elements of mature fibrous tissue, mature adipose tissue, and immature mesenchymal tissue in varying proportions with the additional pseudoangiomatous pattern also reported in some. Immunohistochemical analysis demonstrates reactivity for SMA in mature fibrous tissue, S100 protein in the mature adipose tissue, and variable CD34 reactivity in the pseudoangiomatous foci. The immature mesenchymal tissue is typically SMA negative.[3],[4]

It is noteworthy that when instead of the characteristic triphasic morphology, any one component predominates over others, the lesions can be misdiagnosed as a lipoma/fibroma/fibrolipoma/neuroma. Likewise, lesions that are rich in undifferentiated mesenchymal tissue, can be misinterpreted as malignant.[4]

Infantile fibromatosis is a close differential which has an invasive character and occurs in deeper tissues, mainly striated muscle. Microscopic observation reveals differentiated fibroblasts and their diffuse infiltration among the cells and fibres of striated muscle.

For pseudoangiomatous variant of FHI, Giant cell fibroblastoma (GCF) is a close differential, both clinically and morphologically. However FHIs' unlike GCFs' do not show either the giant cells on histopathology nor the PDGFRB mutations cytogenetically that are characteristic of GCFs'.[3]

FHIs' are usually benign with a good prognosis and rarely relapse if completely excised.[6] Interestingly, compared to a younger tumor that does not have a clearly defined margin, an older tumor is more prone to undergo a successful excision due to pseudoencapsulation.[4]

In conclusion, FHI, though a very rare tumor of infants, should be included in the differential diagnosis in tumors of deep dermal/subcutaneous origin. Though the triphasic histology is very unique, pathologists should be aware of the pseudoangiomatous morphologic variation as seen in our case and reported in a few others, as ignorance of this may lead to an erroneous diagnosis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Coffin CM. Fibrous hamartoma of infancy. In: Fletcher CDM, Bridge JA, Hogendoorn PCW, Mertens F, editors. WHO Classification of Tumours of Soft Tissue and Bone. 4th ed. Switzerland: Lyon Press; 2013. p. 54-5.  Back to cited text no. 1
Saab ST, McClain CM, Coffin CM. Fibrous hamartoma of infancy: A clinicopathologic analysis of 60 cases. Am J Surg Pathol 2014;38:394-401.  Back to cited text no. 2
Al-Ibraheemi A, Martinez A, Weiss SW, Kozakewich HP, Perez-Atayde AR, Tran H, et al. Fibrous hamartoma of infancy: A clinicopathologic study of 145 cases, including 2 with sarcomatous features. Mod Pathol 2017;30:474-85.  Back to cited text no. 3
Yu G, Wang Y, Wang G, Zhang D, Sun Y. Fibrous hamartoma of infancy: A clinical pathological analysis of seventeen cases. Int J Clin Exp Pathol 2015;8:3374-7.  Back to cited text no. 4
Vinayak RS, Kumar S, Chandana S, Trivedi P. Fibrous hamartoma of infancy. Indian Dermatol Online J 2011;2:25-7.  Back to cited text no. 5
[PUBMED]  [Full text]  
Tassano E, Nozza P, Tavella E, Garaventa A, Panarello C, Morerio C, et al. Cytogenetic characterization of a fibrous hamartoma of infancy with complex translocations. Cancer Genet Cytogenet 2010;201:66-9.  Back to cited text no. 6

Correspondence Address:
Preeti Singh
Department of Pathology, M.L.N. Medical College, Allahabad - 211 001, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_272_18

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