Indian Journal of Dental Research

CASE REPORT
Year
: 2008  |  Volume : 19  |  Issue : 3  |  Page : 261--263

Pilomatricoma: A dermal analog of calcifying odontogenic cyst


H Kaveri, A Punnya 
 Department of Oral Pathology and Microbiology, SDM College of Dental Sciences, Dharwad - 580 009, Karnataka, India

Correspondence Address:
A Punnya
Department of Oral Pathology and Microbiology, SDM College of Dental Sciences, Dharwad - 580 009, Karnataka
India

Abstract

Pilomatricoma, also known as «DQ»Calcifying Epithelioma of Malherbe«DQ» is an uncommon, benign, cutaneous tumor originating from the hair matrix. Most often, its precise preoperative diagnosis is not possible. Rarity of this lesion and its histological resemblance to the calcifying odontogenic cyst (the Gorlin«SQ»s cyst) make it relevant, both to the maxillofacial surgeons and the pathologists. Here, we describe a case of pilomatricoma of the periorbital region in a young Indian female patient. We believe that its inclusion is essential in the differential diagnosis of hard masses of the maxillofacial and paraoral regions.



How to cite this article:
Kaveri H, Punnya A. Pilomatricoma: A dermal analog of calcifying odontogenic cyst.Indian J Dent Res 2008;19:261-263


How to cite this URL:
Kaveri H, Punnya A. Pilomatricoma: A dermal analog of calcifying odontogenic cyst. Indian J Dent Res [serial online] 2008 [cited 2022 Sep 27 ];19:261-263
Available from: https://www.ijdr.in/text.asp?2008/19/3/261/42962


Full Text

Pilomatricoma, formerly referred to as "pilomatrixoma" is an uncommon, benign skin tumor thought to arise from hair cortex cells. It accounts for 0.12% of all cutaneous neoplasms and most pilomatricomas occur in the head and neck region. The lesion occurs more commonly in younger age groups with a female and Caucasian preponderance. It typically manifests as a solitary, slow-growing, firm-to-hard nodule with its overlying skin frequently displaying a bluish-red discoloration. Clinically, the lesion is often mistaken for other, more common, skin-based and subcutaneous lesions such as dermoid and sebaceous cysts and lipoma. Surprisingly, a preoperative diagnosis of pilomatricoma is rarely considered by clinicians. [1],[2]

Here, we report a case of pilomatricoma involving the periorbital region in a 13 year-old female patient of Indian origin. There is a need for this rare, distinct entity to be considered by clinicians in the preoperative differential diagnosis of head and neck masses.

 Case Report



Clinical summary: A 13 year-old female patient presented with the chief complaint of swelling in the outer aspect of the left eye since the last year. Clinical examination revealed an ovoid, well-circumscribed swelling measuring 2.5 × 2.5 cm. Overlying skin was erythematous and slightly stretched. The swelling was hard in consistency, nontender and not fixed to the underlying structures [Figure 1]. A provisional diagnosis of a dermoid cyst was made and the lesion was surgically excised.

Histopathological findings: Grossly, the excised specimen was a solitary, well circumscribed, hard, brownish nodule measuring 2.5 cm in diameter. The cut surface of the lesion revealed solid, grayish white-to-brown and firm-to-hard areas. No cystic change was seen. The tissue was routinely processed and embedded in paraffin. Hematoxylin and eosin (H and E)-stained sections were studied. Microscopically, the lesion was well encapsulated and composed of islands of cells separated by fine, fibrovascular connective tissue stroma. The cell islands revealed two distinct cell populations comprising of the basaloid cells located towards the periphery and the ghost/shadow cells occupying the central portion [Figure 2]. The basaloid cells revealed darkly stained, round-to-ovoid, vesicular nuclei with most of them exhibiting prominent nucleoli; the cell borders were ill defined with minimal cytoplasm. The ghost cells located within the centers of the islands revealed an abundant, pale, eosinophilic cytoplasm with well-defined cell borders and a central clear area (Inset, [Figure 2]). Some of them showed only faint traces of nuclear material. Thus, a transition of basaloid cells to ghost cells was noted in many areas of the histological sections. Also noted were areas of keratinization, calcification and focal lymphocytic infiltration along with a foreign body giant cell reaction seen in close proximity to the ghost cells exhibiting keratinization [Figure 3]. The final diagnosis of 'pilomatricoma' was considered based on this varied but characteristic histomorphology.

 Discussion



In 1880, Malherbe and Chenantias described a benign, subcutaneous tumor, which was thought to be of sebaceous gland origin. Since then, this tumor has been referred to as a "Calcifying Epithelioma of Malherbe". In 1922, Dubreuilh and Cazenave described its unique histopathology consisting of basaloid cells and shadow/ghost cells. It was Turhan and Krainer in 1942, who determined that the origin of this neoplasm is from hair cortex cells. Subsequently, Forbis and Helwig in 1961 renamed this neoplasm as "pilomatrixoma", thus avoiding the term 'epithelioma' that carried a connotation of malignancy. This designation was further changed to "pilomatricoma" in 1977, as it was considered more correct etymologically. [1],[2],[3] Gorlin and his associates in 1962, described the "calcifying odontogenic cyst", a distinct odontogenic tumor of the jaws, which is now considered as "an oral analog of pilomatricoma" due to its histological resemblance to pilomatricoma. [4] The incidence of pilomatricoma is estimated to be 1 in 2000 surgical specimens. [5]

Pilomatricoma usually develops within the first two decades of life with 40% of cases occurring before the age of ten years and 60% before the age of 20 years. [3],[5] Some authors have reported a bimodal peak during the first and sixth decades of life. [2] It has a female preponderance with a M:F ratio of 2:3. [2],[5] The most frequent anatomical location is the head and neck region (over 50% of cases), followed by the upper extremities, trunk and the lower extremities. [2] Involvement of the face has been reported in frontal, temporal, cheek, periorbital and preauricular areas. [2]

Clinical presentation is that of a slow-growing, asymptomatic, superficial, mobile, rock-hard mass, ranging in size from 0.5 to 5 cm in diameter with its overlying skin exhibiting a bluish-red discoloration or ulceration. [2],[5] Although it usually presents as a solitary nodule, multiple occurrences and familial cases are also known, generally in association with disorders like Gardner syndrome, Steinert disease, sarcoidosis, Rubinstein-Taybi syndrome and Turner syndrome. [2],[5],[6]

The present case occurred in a 13 year-old female patient of Indian origin and involved the periorbital area. It presented as a solitary, slow-growing, hard mass; there were no other associated findings or similar swellings elsewhere.

Radiographic imaging is of little diagnostic value in pilomatricomas. [6] The role of fine needle aspiration cytology (FNAC) as a preoperative diagnostic investigation has been described. However, the varied histopathological patterns of this tumor can result in cytological sampling errors leading to misdiagnosis, especially if there are no ghost cells in the aspirate. [7] In the present case, a clinical diagnosis of a dermoid cyst was considered and the FNAC was not done.

Varied preoperative clinical diagnoses are considered in a case of pilomatricoma but a surprising finding is that the pilomatricoma has almost never been suspected. [1],[2] The preoperative, differential diagnoses considered by clinicians include dermoid and sebaceous cysts, chondroma, metastatic calcification, osteoma cutis, foreign body granuloma, lipoma and parasitic cyst. [2],[5],[6],[8],[9]

The gross and histopathological features described in literature are similar to those of our case. As the lesion matures, the basaloid cells are transformed to shadow cells; the transition from basaloid to shadow cells can be abrupt or gradual. [7] According to Kaddu et al , [10] pilomatricoma exhibits a distinct histomorphologic spectrum of four stages consisting of early, fully developed, early regressive and late regressive stages. These stages reflect the evolution of the tumor from a matrix cyst to a calcified and ossified nodule with no visible epithelial component. In addition, secondary changes like hemorrhage, ossification, myxoid change, edema and stromal fibrosis have also been described. [1]

Pilomatrix carcinoma, though extremely rare, has also been reported. This malignant counterpart of pilomatricoma is characterized by actively proliferating, hyperchromatic, pleomorphic basaloid cells; atypical mitosis; tumor necrosis, architectural asymmetry and infiltrative growth pattern. It has to be distinguished from the other distinct variant referred to as 'proliferating pilomatricoma,' which is basically a benign tumor. In contrast to a pilomatrix carcinoma, a proliferating pilomatricoma exhibits a relative symmetry, sharp circumscription and a distinct lobular proliferation of basaloid cells with small foci of shadow cells and cells exhibiting variable nuclear atypia and mitosis. [11]

Surgical excision is the treatment of choice - it is relatively easy as the lesion is usually well encapsulated. If the margins are ill defined or adherent to the surrounding tissue, malignancy can be suspected. [2],[7],[8] Occasional recurrences have been reported which are generally due to incomplete excision. [2],[7],[8]

To conclude, pilomatricoma is an uncommon, benign, cutaneous tumor characterized by its histological resemblance to the calcified odontogenic cyst. Most often, its precise preoperative diagnosis is not possible. However, clinicians, in particular, oral and maxillofacial surgeons must be aware of this entity to consider it in the differential diagnosis of hard masses involving the maxillofacial region.

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