Fibroma, acquired (reactive) digitalD23.L

Plaza, 2013

Benign, apparently traumatically induced, circumscribed, acral connective tissue proliferation (tumor cells behave immunohistologically like fibroblasts) of the fingers or toes.

There are solitary, slowly growing 1.0-3.0 cm large, firm, little aching, skin-colored or red nodes with a smooth surface, which apparently start from the palmar or plantar soft tissues of toes of the fingers.

Dense network of compact collagen fibre bundles. The spindle-shaped tumor cells do not show significant cell atypes; they express vimentin and occasionally CD34. They are negative for smooth muscle actin (SMA), desmin, epithelial membrane antigen (EMA), S100 and CD68.

In terms of differential diagnosis, this tumor must be differentiated from other benign or malignant tumors of the acral digiti.

• Ledderhose disease: Mostly starting from the medial part of the plantar aponeurosis. Infestation of the toes is possible in principle but rare.
• Acquired digital fibrokeratome: This benign digital fibromatosis originates primarily from the dorsal and not the ventral parts of the toes/fingers.
• Keloids: Are extremely rare on the fingers and toes.
• Fibromatosis, digital infantile: Rare, benign, fibromatous tumor on fingers or toes in infants and young children, with a tendency to infiltrative growth. Very rare in adults.
• Perneurinoma: Rare tumour originating from the perineural cells. Perineurinomas occur intraneurally in larger nerves, but also in the soft tissue of the extremities, e.g. at the end phalanges of the fingers. Characteristic and evidencing is the formation of structures reminiscent of father Pacini's tactile corpuscles.

1. Gönül M et al (2014) New described dermatological disorders. Biomed Res Int doi: 10.1155/2014/616973
2. Nitzschke Gr et al. (2015) Thick toe - an operative case. Nude Dermatol 41: 375
3. Plaza JA et al (2013) Acquired reactive digital fibroma:
4. a clinicopathologic report of 5 cases of a new entity. J Am Acad Dermatol 69:603-608