Inclusion Body Fibromatosis (Infantile Digital Fibroma)

Definition

• Fibrous and spindle cell lesion primarily of digits of infants, characterized by intracytoplasmic eosinophilic inclusions

Alternate/Historical Names

• Infantile digital fibromatosis
• Recurring digital fibroma
• Reye tumor

Diagnostic Criteria

• Nearly always under 1 year of age
  • May be congenital
  • Rare lesions reported in adults
• Vast majority on 3rd, 4th or 5th digits of hands and feet
  • Rare lesions reported in other sites
  • May be multiple
• May involve dermis and subcutis
• Poorly circumscribed
  • May entrap and surround skin adnexae
• Cellular lesion with bundles of spindle cells
  • Vesicular nuclei
  • Fibrotic stroma
• Perinuclear round eosinophilic inclusions
  • Vary from rare to frequent
  • Approximately size of erythrocytes (3-15 mcrons)
  • Red on trichrome stain
  • Black on iron hematoxylin stain
  • Negative on PAS and Alcian blue stains
  • Similar bodies have been reported in breast phyllodes and fibroepithelial tumors
• Mitotic figures may be present but not atypical
• Virtually always under 2 cm
  • Range 0.3-3.5 cm

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting/updates : 1/11/07, 3/2/08, 1/20/09, 1/29/12

Supplemental studies

Immunohistology

Differential diagnosis

• Infantile fibromatosis
• Fibrous hamartoma of infancy
• Fibroma of tendon sheath
• Palmar fibromatosis
• Infantile fibrosarcoma
• Nodular fasciitis
• Myofibroma
• Neurofibroma
• Leiomyoma

Clinical

• Nearly all under 1 year
• Nearly all under 2 cm
• Vast majority on 3rd, 4th or 5th digits of hands and feet
• Rare lesions reported in adults and other sites
• May be multiple
  • Synchronous or metachronous
• Recurrences do occur but are not destructive; never metastasizes
  • Frequently spontaneous regression

Lists

Predominantly Pediatric Fibrous Lesions

• Calcifying aponeurotic fibroma
• Fibrous hamartoma of infancy
• Gardner-associated fibroma
• Hyaline fibromatosis
• Inclusion body fibromatosis
• Infantile fibromatosis / lipofibromatosis
• Infantile fibrosarcoma
• Myofibroma

Bibliography

• Kempson RL, Fletcher CDM, Evans HL, Henrickson MR, Sibley RS. Tumors of the Soft Tissues, Atlas of Tumor Pathology, AFIP Third Series, Fascicle 30, 2001
• Fletcher CDM, Unni KK, Mertens F. Pathology and Genetics of Tumours of Soft Tissue and Bone, World Health Organization Classification of Tumours 2002
• Weiss SW, Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors, 4th edition, 2001
• Bittesini L, Dei Tos AP, Doglioni C, Della Libera D, Laurino L, Fletcher CD.  Fibroepithelial tumor of the breast with digital fibroma-like inclusions in the stromal component. Case report with immunocytochemical and ultrastructural analysis.  Am J Surg Pathol 1994 Mar;18(3):296-301
• Mukai M, Torikata C, Iri H, Hata J, Naito M, Shimoda T.  Immunohistochemical identification of aggregated actin filaments in formalin-fixed, paraffin-embedded sections. I. A study of infantile digital fibromatosis by a new pretreatment.  Am J Surg Pathol 1992 Feb;16(2):110-5 
• Canioni D, Richard S, Rambaud C, Manach Y, Nezelof C.  Lingual localization of an inclusion body fibromatosis (Reye's tumor).  Pathol Res Pract 1991 Sep;187(7):886-9 
• Choi KC, Hashimoto K, Setoyama M, Kagetsu N, Tronnier M, Sturman S.  Infantile digital fibromatosis. Immunohistochemical and immunoelectron microscopic studies.  J Cutan Pathol 1990 Aug;17(4):225-32 
• Viale G, Doglioni C, Iuzzolino P, Bontempini L, Colombi R, Coggi G, Dell'Orto P.  Infantile digital fibromatosis-like tumour (inclusion body fibromatosis) of adulthood: report of two cases with ultrastructural and immunocytochemical findings.  Histopathology 1988 Apr;12(4):415-24 
• Yun K.  Infantile digital fibromatosis. Immunohistochemical and ultrastructural observations of cytoplasmic inclusions.  Cancer 1988 Feb 1;61(3):500-7 
• Fringes B, Thais H, Bohm N, Altmannsberger M, Osborn M.  Identification of actin microfilaments in the intracytoplasmic inclusions present in recurring infantile digital fibromatosis (Reye tumor).  Pediatr Pathol 1986;6(2-3):311-24
• Purdy LJ, Colby TV.  Infantile digital fibromatosis occurring outside the digit.  Am J Surg Pathol 1984 Oct;8(10):787-90 
• Allen PW.  Recurring digital fibrous tumours of childhood.  Pathology 1972 Jul;4(3):215-23
• Grenier N, Liang C, Capaldi L, Ney A, Lapidus C, Schappell D, Katarincic J, Robinson-Bostom L. A range of histologic findings in infantile digital fibromatosis. Pediatr Dermatol. 2008 Jan-Feb;25(1):72-5.
• Hiraoka N, Mukai M, Hosoda Y, Hata J. Phyllodes tumor of the breast containing the intracytoplasmic inclusion bodies identical with infantile digital fibromatosis. Am J Surg Pathol. 1994 May;18(5):506-11.
• Laskin WB, Miettinen M, Fetsch JF. Infantile digital fibroma/fibromatosis: a clinicopathologic and immunohistochemical study of 69 tumors from 57 patients with long-term follow-up. Am J Surg Pathol. 2009 Jan;33(1):1-13
• Thway K, Gibson S, Ramsay A, Sebire NJ. Beta-catenin expression in pediatric fibroblastic and myofibroblastic lesions: a study of 100 cases. Pediatr Dev Pathol. 2009 Jul-Aug;12(4):292-6.
• Thway K, Fisher C, Sebire NJ. Pediatric fibroblastic and myofibroblastic lesions. Adv Anat Pathol. 2012 Jan;19(1):54-65.