Dermatofibroma is a variety of dermatological tumors that develops in the subcutaneous tissue. Benign fibroblast histiocytoma of the dermis, surface-level benign fibrous histiocytoma, or ordinary fibrous histiocytoma are all terms used to describe dermatofibroma.

Clinically, these mesenchymal cell tumors of the skin are solid visceral masses that most commonly arise on the extremities and may or may not be coupled with underlying cutaneous abnormalities. They are normally painless and tiny, with a diameter of just under or similar to one centimeter.

Rather than identifying the biological origin, the title “fibrous histiocytoma” speaks to the morphologic shape of the cellular components that make up these tumors.

Dermatofibromas are thought to be caused by two different processes:

• The clonal process vs. the reactive
• Neoplastic proliferation

Each of these ideas has evidence to support them. Patients with dermatofibromas frequently describe a history of possibly triggering regional trauma, such as an animal bite or a shallow puncture wound caused by thorny or wooden fragments.

Dermatofibromas can affect persons among all generations, though they are more prominent in women in their 20s and 40s. They also affect women more than men, with some studies claiming a 2:1 female to male ratio. Although they are benign tumors, there were reports of tumor recurrence and, much more infrequently, metastatic disease.

Differentiating dermatofibroma versus dermatofibrosarcoma’s protuberans, a nearly identical but also more malignant epidermal cancer, is critical when evaluating the diagnostic evaluation of these tumors.

Dermatofibromas are a frequent dermis cancer in practically all populations, accounting for three percent of all dermatopathology samples in the lab, according to one study. Because most patients are symptomless, it’s impossible to estimate the global incidence because many people are unwilling to receive treatment for this tumor.

Patients in their twenties to forties are the most likely to develop these lesions. The number of research shows a female superiority, with rates ranging from borderline to marginally greater in females to as much as twice as prevalent in females as in males.

A limited expansion of spindle-shaped fibroblasts hybridized with histiocytoid cells within the skin characterizes the common dermatofibromas clinical features. This growth is often nodular in morphology, with spiculated yet somewhat defined edges that push against the surrounding skin.

The spindle cells will produce a central “storiform” structure, which characterizes the extended nuclei as having a multi-centric whorling shape. There could be lymphocytes and capillaries jumbled together, or multinucleated large cells.

These proliferations are normally kept inside the skin, however, a tiny piece of the disease plunging down into the subcutaneous layer following septum borders is not rare.

The presence of entrapped collagen fibers or “collagen spheres” beneath and between the fascicles of spindled fibroblasts is a beneficial and differentiating feature. These enclosed collagen clusters are more likely to occur on the lesion’s perimeter.

The “Grenz zone,” a clearly demarcated and undisturbed zone of separation, usually separates the underlying dermis. Acanthosis and hyperpigmentation are two common reactive skin alterations. Extended rete grooves plunging into the skin with hyperpigmented basal keratinocytes, often known as the “dirty feet” indication, can be seen in the skin.

The most crucial thing to separate dermatofibromas from is the dermatofibrosarcoma protuberans, which look similar but are considerably more dangerous (DFSP).

These abscesses are more granular, have a distinct storiform appearance, and deeply infiltrate and penetrate the subcutis, enclosing adipose as it deepens and continues to spread along the dermal septae.

The cause of dermatofibromas is still a subject of debate. Dermatofibroma patients frequently report having experienced local trauma. The history supports a reactive approach. However, only about a fifth of cases have a history of local trauma that is properly reported.

There is usually no triggering event or trauma, and the dermatofibroma develops independently. Surprisingly, spontaneous regression is uncommon, while they will form spontaneously, which may support an argument for a clonal or neoplastic model over a purely reactive approach.

Certain investigators have used X-chromosome inactivation to identify clonal markers in dermatofibromas cells, arguing for a monoclonal pattern and possibly favoring a neoplastic process as the basis of dermatofibromas growth. Others believe that dermatofibromas are derived in a variety of ways.

Within the same lesion, they represent both a reactive and a neoplastic phase, with the histiocytoid component being neoplastic and the fibrous portion exhibiting reactive fibroblastic growth.

Many dermatofibromas appear as single lesions, with approximately 10% of instances appearing as multiple lesions at the same time. Interestingly, despite the fact that there are different histologic benign forms of dermatofibromas, lesions in patients who have two or more dermatofibromas at the same time tend to seem histopathologically identical.

Dermatofibromas are benign tumors that have a good prognosis. Some lesions even disappear on their own, resulting in hypopigmented skin. Most dermatofibromas will remain stable for many years.

These lesions seldom recur after complete excision, and only the most aggressive kinds exhibit local recurrence in about 20% of patients. These tumors rarely spread to other parts of the body.

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https://www.ncbi.nlm.nih.gov/books/NBK470538/