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Journal of Medical Cases

Case Report

Volume 5, Number 8, August 2014, pages 466-469

Challenging Diagnosis of a Rare Case of Spontaneous Keloid Scar

Keloid scar is a clinical diagnosis, usually preceded by a history of localized injury [1]. The term keloid was originally described in 1800s as “cheloid”, derived from the Greek word “chele” meaning “crab claw” because of its lateral extensions resembling the legs of a crab growing into normal tissue [2, 3]. This invasion of surrounding dermis extension has become the pathognomonic feature of a keloid scar [4].

Keloid scar usually appears as firm, broad nodule and often erythematous with a shiny surface. Because of its common, non-specific clinical appearance and difficulty in treatment, it is important to differentiate keloid scar from other malignant or benign tumors [5, 6]. The misdiagnosis of keloid scar for a tumor will have significant consequences as demonstrated in our case below.

One of the most important indicative information that leads to keloid scar diagnosis is the history of some form of injury prior to the appearance of the lesion [7]. Spontaneous keloid scars, that is, those keloidal lesions that develop without previous injury or surgery, are rare [8]. Here, we presented a rare case of spontaneous keloid scar on the unusual site of preauricular area of a 13-year-old boy without history of previous injury, and underlined its diagnostic challenge.

A 13-year-old boy was referred to Plastic and Reconstructive Surgery Unit for the management of left preauricular nodule (Fig. 1). The nodule had been present for 3 years. It started as a small, inconspicuous lesion that gradually increased in size. There was no associated pain or discharge. There was also no history of injury or past keloid scarring. The lesion was biopsied by the referring hospital and reported as desmoid-type fibromatosis (DF). Otherwise, the patient was healthy with unremarkable past medical history. There was no family history of keloid scarring or fibromatosis. No syndromic features were detected.

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Figure 1. Preauricular nodule over the left cheek with no history of trauma. Note the pinkish mark overlying the skin of the nodule that indicated the site of biopsy.

On examination, a well-circumscribed nodule measuring 3 × 4 cm was noted over the left preauricular region. The overlying skin appeared normal with the exception of a pinkish, flat scar over the nodule that marked the site of previous incisional biopsy by the referring hospital. The nodule had a firm consistency but mobile. There was no evidence of infiltration to the adjacent tissue. There was also no palpable cervical lymphadenopathy.

Surgical excision and skin grafting were planned as primary management to achieve tumor clearance. Intraoperatively, the lesion was excised with a margin of 1 cm and down to the parotidomasseteric fascia (Fig. 2). The specimen was sent for histological analysis. The resultant defect was resurfaced with full thickness skin graft, taken from the left supraclavicular area (Fig. 3). The skin graft was secured with 5/0 vicryl suture, and 3/0 silk as tie-over bolus dressing.

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Figure 2. The lesion was excised with 1 cm peripheral margin and down to the parotidomasseteric fascia.

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Figure 3. The preauricular defect was resurfaced with full thickness skin graft, taken from left supraclavicular region. The skin graft was secured with 5/0 vicryl suture and 3/0 silk as tie over bolus dressing.

Postoperatively, the skin graft was fully integrated and the course of recovery was unremarkable. The histopathology report of the specimen revealed it to be a keloid scar. At 3-month follow-up, the patient developed an oval-shaped ring of keloid scar, sparing the central portion of the graft (Fig. 4). The keloid scar was treated with topical silicon cream and intralesional steroid injection.

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Figure 4. The formation of oval-shaped ring of keloid scar over the left preauricular region. The shape of the ring of keloid scar corresponded to the edge of the full thickness skin graft.

Keloid scars are benign dermal collagenous lesions that arise in the reticular layer of the dermis during a prolonged wound healing process as the connective tissues response to trauma, inflammation, surgery or burns [9, 10]. It often persists at the site of injury, has a high incidence of recurrence after excision, and always overgrows the boundaries of the original wound [9]. Clinically, it is typically raised, red or pink, and sometimes pruritic and painful [10]. The variability of the morphology of keloid scars is due to their evolving nature as a result of the extensibility of topical skin and the influence exerted by the external forces from adjacent joints and muscles based on their anatomical location [9]. It almost appears mushroom-shaped at first and subsequently, assumes specific forms such as butterfly-shaped in the mid chest area, propeller-shaped over the deltoid region, and bulbous on the earlobe including being nodular on the face as in our case.

The occurrence of keloid scar is commonest in patients 10 - 30 years of age [4]. It has a predilection for anterior chest especially presternal area, shoulders, upper arm, upper back, back of the neck and earlobes [2, 11]. Individuals of all ethnic backgrounds can form keloid scars but it is 15 times more prevalent in black population than in white [2, 3]. It is also more common in teenager during puberty and women during pregnancy [3].

The cause of keloid scars remains largely unknown and no single hypothesis can sufficiently explained its formation [5]. The pathogenesis of keloid scar is complex, which involves the interplay of multiple factors such as genetic, hormonal, immunogenic and environmental factors [2]. There are theories such as the collagen turnover hypothesis, the tension hypothesis, the genetic immune dysfunction hypothesis and the sebum reaction hypothesis, but none solely accounted for their pathogenesis [12]. Patients, who are syndromic, are also more susceptible [13].

To date, there has been very few isolated spontaneous keloid scar cases reported in the literature [5, 14]. We reported a case of a 13-year-old boy with unexpected spontaneous keloid scar on the left preauricular region of the cheek without being preceded by any injury. The patient did not have family history of keloid scarring nor had he history of previous keloid scar formation elsewhere on his body. The location of keloid scar on the left preauricular region was very unusual. To our knowledge, there has not been any case of keloid scar described over the preauricular region in the literature. Other than his age as teenager in which keloid scar is known to affect, he had no known risk factor for keloid scarring [3]. His diagnosis was, therefore, challenging because of the unsuspected anatomical site involved and the absence of history of skin injury or family history of keloid scarring.

As a result of the rarity of spontaneous keloid scar, it is important to bear in one’s mind the differential diagnosis of lesions resembling keloid scar. This is particularly important because various malignant and benign tumors can mimic keloid scar [5, 6]. This is exemplified in our case in which the initial biopsy revealed it as DF. Among the malignant tumors that mimic keloid scars are dermatofibrosarcoma protuberans, trichilemmal carcinoma and keloidal basal cell carcinoma [5]. In addition to malignant skin conditions, there are a few benign conditions that also clinically resemble keloid scar [5, 6]. These included nodular scleroderma, keloidal scleroderma, sclerotic neurofibroma, keloidal granuloma, erythema elevatum diutinum, dermatofibroma, penile edema, pseudoangiomatous hyperplasia, lichen sclerosus, apocrine cystadenoma, adult-onset juvenile xanthogranuloma, chondroid syringoma and subcutaneous eosinophilic lymphoid granuloma [5].

In general, a decision to biopsy a keloid scar should not be taken lightly because even a small wound from a minor surgical procedure may promote keloid scar growth [5]. However, biopsy for anomalous or unusual cases of keloid scar is justified [5]. In our case, histological biopsy was obtained by the referring hospital to confirm the diagnosis of the keloid scar due to its unusual location over the preauricular region, the absence of a past history of injury or trauma and the lack of significant predisposing factors. Unfortunately, the biopsied specimen was diagnosed histologically as DF.

DF is a rare monoclonal proliferative disease of fibroblastic origin [15]. Although it is a benign tumor, it is regarded as an aggressive tumor because of their locally infiltrative growth and high recurrence rate. Its mainstay of treatment remains surgical with wide resection margins advocated [16]. This had led us to excise the lesion with 1 cm margin and down to parotidomasseteric fascia.

Unfortunately, it is not always easy to make an accurate diagnosis of keloid scar based on its clinical appearance or even histopathologically especially due to its evolving nature [17, 18]. This fact is highlighted in our case in which a histological misinterpretation of the biopsied specimen occurred. The accurate diagnosis of keloid scar carries significant implication, because a misdiagnosis will subject the patient to unnecessary biopsy or excision, which is illustrated in our case, can cause significant disfigurement through its recurrence. Our case, therefore, highlighted the challenge of managing keloid scar as an entity and more vigilance should be held in our practice while acknowledging the possible spontaneity of their occurrence.

Spontaneous keloid scars pose a significant diagnostic challenge to any clinician. Because of their rarity and variability in their clinical course, attending clinician should exercise a careful note when treating this condition. Any misstep along the way can lead to costly and disfiguring outcomes. All clinicians should be extra vigilant and the spontaneity nature of keloid scarring should continue to remain in one’s mind.

Grant Support

Not applicable.

Conflict of Interest

Nil.

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