|LETTER TO EDITOR
|Year : 2016 | Volume
| Issue : 2 | Page : 100-101
Cellular dermatofibroma of post auricular region: An unusual presentation
Department of Pathology, Prasad Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
|Date of Web Publication||25-Oct-2016|
521/177, Bhairon Prasad Marg, Bara Chand Ganj,Lucknow, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Awasthi N. Cellular dermatofibroma of post auricular region: An unusual presentation. Saudi J Health Sci 2016;5:100-1
Dermatofibromas are commonly seen benign cutaneous lesions encompassing several histopathological variants such as fibrocollagenous, lipidized, cellular, histiocytic, aneurysmal, angiomatous, clear cell, myxoid, keloidal, monster, osteoclastic, epithelioid, palisading, and mixed. These tumors have a preponderance in female gender and a predilection for the extremities.  Cellular dermatofibroma constitutes about 5% of cutaneous dermatofibromas. ,
A 17-year-old female presented to the surgical outpatient department with a swelling behind her right ear for the past 2 years. There were no other associated symptoms or any preceding history of trauma. Local examination showed a 0.8 cm × 0.5 cm firm, nontender, right postauricular swelling which was clinically thought to be an enlarged lymph node. The swelling was excised in multiple pieces, under local anesthesia and sent for histopathological examination.
Macroscopic examination showed multiple firm tissue pieces, one with attached skin, collectively measuring 0.5 cm × 0.5 cm × 0.2 cm. Microscopic examination showed few fragmented tissue pieces from a benign dermal tumor, lined by hyperkeratotic stratified squamous epithelium showing increased basal pigmentation and flattened rete ridges. The lesion was noncapsulated, poorly circumscribed, composed of plump to spindled, fibrohistiocytic cells arranged in fascicular to storiform pattern, separated from the epidermis by lymphocytic infiltrate and dermal collagen bundles. Few multinucleated giant cells were also seen. Infiltration of superficial subcutaneous fat in a lace-like pattern was evident along with focal areas of hemorrhage, hemosiderin deposition, and few mitosis [Figure 1]. Keeping in view the characteristic histopathological findings a diagnosis of cellular dermatofibroma was rendered.
Dermatofibromas commonly present as solitary, slow growing dermal nodule on extremities of young to middle-aged males. A cellular variant of dermatofibroma may occur at unusual sites such as the face, ears, hands, and feet.  Unlike conventional fibrous histiocytomas, characteristic histomorphological features of cellular dermatofibromas as seen in the present case also are higher cellularity, higher mitotic activity, a deeper (subcutaneous) tumor extension and presence of peripheral hyalinized collagen bundles. Apart from this a more fascicular growth pattern, a higher tendency to exhibit an epithelioid cell component, the possibility of undergoing central necrosis (10-20% of cases) and occasional epidermal ulceration or reactive hyperplasia have also been documented. , Recognition of this variant is important particularly because of its high rate of local recurrence (25%) after incomplete excision as compared to benign fibrous histiocytomas (<2%). ,
|Figure 1: (a) Low power view (H and E, ×100) showing a dermal tumor separated from the epidermis by a grenz zone. (b) High power view (H and E, ×400) showing a cellular tumor composed of spindle cells with focal storiform pattern. (c) High power view (H and E, ×400) showing a multinucleated giant cells. (d) High power view (H and E, ×400) showing superficial infiltration of subcutaneous fat|
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The most important differential diagnosis is with dermatofibrosarcoma protuberans. CD34 and factor XIIIa have been widely used to distinguish cellular dermatofibroma from dermatofibrosarcoma protuberans.  Due to financial constraints of the present patient immunohistochemistry could not be done. Although nature of cellular dermatofibroma is invariably benign, there have been few case reports describing the metastatic potential of these tumors.  Till date, very few cases of dermatofibroma have been described in this location.
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