Digital Fibromatosis (Infantile Digital Fibromatosis)

 No nuclear β-catenin labeling but cytoplasmic labeling common



• Inclusions show granular &/or filamentous features by EM

• Cytoplasmic filaments extend onto inclusions



image
Infantile Digital Fibromatosis/Inclusion Body Fibromatosis
Clinical examination of infantile digital fibromatosis shows an exophytic, dome-shaped superficial neoplasm, which presents in infants and small children.


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Infantile Digital Fibromatosis, Low Magnification
At low magnification, the lesion is plastered against the overlying skin image. Because it is pale, tiny capillaries image are readily apparent even at low magnification. This example has a surface erosion with exudate image.

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Infantile Digital Fibromatosis, Storiform Architecture
Note the storiform pattern of this tumor at intermediate magnification. The process is myofibroblastic, so it is not as brightly eosinophilic as a smooth muscle tumor.

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Infantile Digital Fibromatosis, Cytologic Features
Note the eosinophilic inclusion bodies image, which consist of actin filaments. They are not as eosinophilic as erythrocytes image. This image also shows the delicate nuclear chromatin in the myofibroblastic cells image of the lesion. Most of the nuclei display delicate nucleoli.


TERMINOLOGY


Synonyms




• Infantile digital fibromatosis
image Infantile digital fibroma

• Digital fibrous tumor of childhood
image Recurring digital fibrous tumor of childhood

• Inclusion body fibromatosis (term used by World Health Organization)


Definitions




• Benign proliferation of fibroblasts and myofibroblasts, containing scattered eosinophilic spherical inclusions, that arises on digits (both fingers and toes) of young children


CLINICAL ISSUES


Epidemiology




• Incidence
image Rare fibroblastic/myofibroblastic neoplasm

• Age
image Most cases occur in 1st year of life, occasional cases in older children

image Very rare in adult patients

• Sex
image M = F


Site




• Dorsal aspects of hands or feet most common

• Rarely synchronous or asynchronous involvement of > 1 digit

• Thumb or great toe is only very rarely affected

• Extradigital soft tissues (i.e., arm, breast) are only extremely rarely affected


Presentation




• Digital enlargement

• Dome-shaped swelling overlying phalanges or interphalangeal joints

• Nontender nodules

• Rarely erosion of bone


Natural History




• May recur locally

• May regress spontaneously

• No progression

• No metastases


Treatment




• Surgical approaches
image Local excision with preservation of function


Prognosis




• Excellent overall prognosis

• May recur locally

• May show spontaneous regression

• Main prognostic indicator is adequacy of primary excision


MACROSCOPIC


General Features




• Ill-defined neoplasm

• Dermal-based neoplasm with gray-white, indurated cut surface covered by intact skin

• No areas of hemorrhage

• No areas of necrosis


Size




• Nodules of variable size
image Usually measure < 2 cm


MICROSCOPIC


Histologic Features




• Dermal tumor composed of infiltrating fascicles and sheets of spindle cells
• Uniform-appearing spindle-shaped fibroblasts and myofibroblasts

• No significant cytologic atypia

• Elongated spindled nuclei

• Pale eosinophilic, fibrillary cytoplasm

• Intracytoplasmic eosinophilic spherical inclusions

image Often show perinuclear localization

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Digital Fibromatosis (Infantile Digital Fibromatosis)
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