|Year : 2018 | Volume
| Issue : 3 | Page : 125-127
Giant pilomatrixoma: A rare case with diagnostic difficulties
Department of Plastic Reconstructive Aesthetic Surgery, Balikesir Atatürk City Hospital, Balikesir, Turkey
|Date of Web Publication||2-Jul-2018|
Department of Plastic Reconstructive Aesthetic Surgery, Balikesir Atatürk City Hospital, Balikesir
Source of Support: None, Conflict of Interest: None
Pilomatrixomas are benign subcutaneous masses that originate from the hair follicle. Dimensions do not exceed three cm. When the dimensions exceed five cm, it is called giant pilomatrixoma and is very rare. Giant PMs (pilomatrixomas) can be confused with malignancy due to their locally aggressive features and nonspecific citopathologic and radiologic findings. By presenting a 62 years old men who has a giant PM phenomenon settled in the upper extremity, we wanted to observe the difficulties encountered in the diagnosis in the light of the literature.
Keywords: Diagnose, giant, pilomatrixoma
|How to cite this article:|
Can B. Giant pilomatrixoma: A rare case with diagnostic difficulties. Turk J Plast Surg 2018;26:125-7
| Introduction|| |
Pilomatrixomas are benign subcutaneous masses that originate from the hair follicle. They are often seen in the first two decades, but they can occur at any age. They are usually located in the head, neck, and upper extremities. Dimensions do not exceed 3 cm. When the dimensions exceed 5 cm, it takes the name of giant pilomatrixoma and is very rare. Giant PMs can be confused with malignancy, especially when seen in older ages due to their rapid growth, their ability to cause discoloration and ulceration on the skin and their hardness. The absence of specific radiological findings also makes preoperative planning difficult. By presenting a giant PM phenomenon settled in the upper extremity, we wanted to observe the difficulties encountered in the diagnosis in the light of the literature.
| Case Report|| |
A 62-year-old healthy male individual applied with a hard, mobile mass that grew rapidly for 8 months, 120 mm × 62 mm × 40 mm in size and formed a pink-purple discoloration on the lateral surface of the right arm [Figure 1]. Upper extremity neurovascular examination was normal. There was no axillary lymphadenopathy. The patient had no systemic complaints. With superficial tissue ultrasonography (USG), it was stated that the mass showed increased vascularity and heterogeneous structure. The sarcomatous lesions should be considered in differential diagnosis. Magnetic resonance (MR) imaging could not be performed due to the buckshot due to the gunshot wound he had in years ago in the vertebral region of the patient. With these findings, the patient was scheduled for excision. With a 5 mm margin, the mass was excised along with the skin with a sharp dissection over the muscle fascia. Cross-section was performed to examine the internal structure of the mass [Figure 2]. It was observed that the mass had a significant capsule and a considerably significant heterogeneous internal structure. The defect area was repaired with split-thickness skin graft. The pathology result was pilomatrixoma. There were no problems in the 2 years' follow-up of the patient [Figure 3].
| Discussion|| |
Pilomatrixoma was first described by Malherbe in 1880 as calcific epithelioma of Malherbe. In 1949, Lever and Griesember proposed the name of the pilomatrixoma to emphasize the origin of the tumor that is originating from the hair follicle. , They clinically distinguish as hard, painless, slow-growing benign subcutaneous masses usually not exceeding 3 cm. They constitute 1% of all skin tumors.  About 60% of the PMs appear in the first two decades and show mild female predominance. They are often located in the head, neck, and upper extremities.
The Giant PM term was first put forward by Krausen et al. in 1974.  Although there is no accurate definition of giant PM, the PMs with dimensions over 5 cm are called giant PM. ,,,,, They form 10% of all PMs.  Giant PMs can be confused with malignancy due to rapid growth, local aggressive course, discoloration, and ulceration of the skin, especially when seen in older ages.
Julien and Bowes reported that only 21% of giant PMs were diagnosed correctly before treatment.  In Demirdφver et al., a study on the giant PM of the arm, this rate is reported as 40%.  Due to the low rate of diagnosis, especially ύn the advanced age group, PMs can be confused with skin malignancies.
There are a number of cases in the literature that address this confusion in diagnosis. In a case presented by Prendes et al., in 2012, a subcutaneous needle aspiration biopsy was performed to the patient who applied with a subcutaneous mass in the posterior cervical region.  The result was squamous cell carcinoma metastasis. The patient was scanned with whole-body positron emission tomography, and neck MR, laryngoscopic, and endoscopic examinations were done. No primary focus was found. Then, the mass was excised and sent to histopathological examination and the result was pilomatrixoma. In the study, it was stated that PMs may demonstrate cytopathologic similarities to malignancy, thus emphasizing that fine needle aspiration biopsy may be misleading.
A similar case is presented in our country. In 2017 Temel et al. applied total excision to the case who was referred with parotid mass and reported as malignant epithelial tumor as a result of fine-needle aspiration biopsy. After total excision, the histopathologic examination was done, and the result was pilomatrixoma.  In the study, it was emphasized that the tumor has heterogeneous structure. They stated that if the atypic mitosis predominates in the zone where FNA biopsies were taken, the tumor may be mistakenly evaluated as malignant. The definite diagnosis of pilomatrixomas, therefore, can be made with total excision.
Honda et al. reported in their literature analyze in 2016 that the cytopathologic features of giant PMs were similar to squamous cell carcinoma (SCC) at %31.2.  For this reason, it has been emphasized that fine needle aspiration biopsy should not be used for giant PM diagnosis and histopathological examination is the most reliable one.
Giant PMs also exhibit nonspecific properties radiologically. In our case, it was stated that mass may be in malign nature with preoperative superficial tissue USG. Giant PMs appear to be heterogeneous and vascular masses with subcutaneous, solid, and cystic components in USG, which can be confused with malignancy. MR and computed tomography also show very nonspecific features. For example, in the study of a giant PM located in the gluteal region in 2015, the patient's MR revealed that the mass was in malign type.  For giant PMs, radiological examinations have a role in determining the depth of the tumor and the proximity to the important structures, rather than being diagnostic.
Giant PMs have similarities with malignancy, due to the fact that they may show local aggressive properties. Often, they cleave into the skin on top. They cause red-purple discoloration on the skin. Occasionally, they may also cleave into base tissues. In this case, treatments may require aggressive surgery, such as malignant tumors. In the literature, a giant PM was found that affected the parotid gland and temporal bone, causing peripheral facial paralysis and hearing loss. The case was treated with partial parotidectomy and mastoidectomy. 
The treatment of giant PMs is surgical excision. Excision is recommended along with the skin if the skin on top of it shows adherence. However, there is no consensus on the safety margin in the literature. When the lesion is completely removed, relapse is very rare (0%-3%). ,[5-11] However, different safety margins such as 4-6 mm and 1-2 cm are recommended in studies. , Nadershah et al. suggested that a 2 cm safety margin is unnecessary for benign lesions where recurrence is fairly low.  He also suggested that this margin should be applied for recurrent lesions or lesions that cannot be distinguished preoperatively whether malignant or benign.
As a result, giant PMs are rare, but they may be confused with malignancies, especially when seen in older age groups. Histopathology is necessary for definitive diagnosis. Therefore, if definitive preoperative diagnosis is necessary, incisional biopsy should be preferred instead of fine-needle aspiration. Radiological examinations can be used to determine tumor depth and proximity to important structures. The treatments are the surgery. For primary lesions, the total excision is sufficient with the safety margin of 4-6 mm.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]