Rare diseases · Sign or symptom
Inclusion body fibromatosis
HP:0025197
What it means
A benign tumor made up of mostly myofibroblasts that appears almost exclusively on the digits of the hands and feet, rarely involving the thumb or big toe. The lesion displays a proliferation of bland intradermal spindle cells arranged in whorls, fascicles, or a storiform pattern in a collagenous background of varying degrees. Also usually present are perpendicular tumor cell fascicles that extend to the epidermis. The small intracytoplasmic inclusions are said to appear similar to red blood cells. The inclusion bodies have been shown to be made up of densely packed vimentin and actin filaments. The tumor often causes a dome-shaped elevation of the overlying structures, forming a protuberant or polypoid nodule. The overlying epidermis can display a host of changes, including acanthosis, hyperkeratosis, parakeratosis, rete ridge flattening, entrapment of adnexal structures, and, rarely, ulceration.
Rare diseases that can present with this1
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Digital fibrous tumor of Reye · Digital fibrous tumour of Reye · Infantile digital fibroma · Infantile digital fibromatosis
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.