INTRODUCTION

Dermatofibroma is a benign growth of oval cells in the dermis that resemble histiocytes and spindle cells that resemble fibroblasts. It is sometimes referred to as benign fibrous histiocytoma or sclerosing hemangioma [1].

The majority of FHs affect young to middle-aged persons, and they are more common in women. Male young adults are more likely to have cellular and atypical FHs [2].

Cellular, atypical, and aneurysmal variants that are significant in terms of clinicopathology are rare. Less than 5% of cases are cellular dermatofibroma; aneurysmal and atypical dermatofibromas are less prevalent than cellular dermatofibromas [2].

The clinical appearance is typically characteristic enough to allow for a clinical diagnosis. Dermatofibroma often manifests as a single, reddish-brown, round or ovoid papule or nodule that is 0.5–1 cm in diameter and occasionally has a yellowish color. The dimple sign was coined by Fitzpatrick to describe the indentation that forms over a dermatofibroma when it is lightly held between the thumb and forefinger [3].

Generally, there are two options: either no treatment at all or excision for cosmetic or differential diagnosis clarity [4].

CASE REPORT

A fifty-year-old male in good health had an asymptomatic recurring lesion on the upper part of his right leg assessed for a period of one year (Figs. 1a – 1c). The patient denied having ever experienced trauma in the location. An indurated, raised, brown, hyperkeratotic plaque was found upon examination. The patient had a history of lesion removal from a non-dermatology-practicing clinician. There was no palpable lymph node inguinal. A differential diagnosis of dermatofibroma, clear cell acanthoma, keratoacanthoma, and warty dyskeratoma was made based on an excision biopsy. Under the microscope, the section displayed (Figs. 2a – 2b) acanthotic skin with spindle cell growth without atypia mixed with foamy, hemosideren-laden histocytic cells with peripheral collagen entrapment. The lesion was separated from the epidermis by an unremarkable dermal border zone. Immunohistochemistry: S100 focal positive, CD34 negative, CD68 positive in histocytes. The diagnosis was consistent with cellular dermatofibroma.

	Figure 1: (a-c) Brown, indurated plaque 0.5 x 1 cm in size, with a hyperkeratotic surface, on the upper leg.
	Figure 2: (a and b) Histopathological view under H&E stain displaying acanthotic skin with spindle cell growth without atypia mixed with foamy, hamosideren-laden histocytic cells with peripheral collagen entrapment. The lesion was separated from the epidermis by an unremarkable dermal border zone.

DISCUSSION

The exact etiology of dermatofibroma is unknown yet it is thought to represent a reactive and/or neoplastic process [2].

Although it may also form on the face, ears, scalp, hands, and feet, CDFs are more commonly encountered on the extremities [5].

Several clinical and histopathological variants exist (Table 1) [3].

Table 1: Clinical and histopathological variants of dermatofibroma.

CDF and BFH may be distinguished from one another by a number of characteristics features: a greater average size (2 cm vs. 0.8 cm), more cellularity, a high rate of mitosis, the potential for focal necrosis, restricted cellular polymorphism, and a common extension into superficial fascia and fat [6,7].

These characteristics may lead to the initial misdiagnosis of CDF as dermatofibrosarcoma protuberans (DFSP). The name indeterminate fibrohistiocytic lesion is occasionally used to describe CDF since it shares histologic and immunopathologic traits with DFSP [8]. Stains from immunohistochemistry may be utilized to aid in differentiation. The majority of CDF have been observed to stain positive for factor 13a, while DFSP more frequently express CD34 and CD163 [9,10].

There have been reports of finding human progenitor cell antigen (CD34) in DFSP with 50% to 100% of reactive cells while dermatofibromas were reported to only have focal reactivity (< 20% positive cells) [11].

Comparing cellular DF to classic DF, which has a minimal risk of recurrence (2% – 3%) even if it is incompletely excised, the recurrence rate of cellular DF is reported to be as high as 26% [12,13].

Every case that returned was at the location of an earlier biopsy or partial excision. No specific anatomical site was more likely to reoccur. Every case that had a recurrence was local, occurring in the same site as an earlier biopsy or excision. The only characteristic that distinguished recurring lesions from non-recurrent ones was size. Lesions that did not recur had an average beginning size of less than 1 cm, while lesions that did recur had an average initial size of more than 1 cm [14].

There are a total of eleven examples in the literature in which CDF metastasized to other organs, including the liver, lymph nodes, soft tissues, and lungs [14].

There is controversy on the best way to manage cellular DF. Authors advise total excision or Mohs’ micrographic surgery as the treatment for cellular DF due to infrequent reports of metastases and malignant transformation, particularly, in instances with an aggressive development pattern [13,14].

Others mention that a large excision of more than 10 mm is a more appropriate modality. Observation is still an acceptable option, particularly, in cases when immunostaining confirms the diagnosis of a benign lesion [15].

CONCLUSION

Cellular dermatofibroma is considered a benign tumor. There is ongoing debate on treatment approaches; some reduce the chance of recurrence to 10%. There have been no cases of metastatic or fatal lesions, and the patient may still be reassured with follow-up.

REFERENCES

Notes