Perforating pilomatricoma

Pilomatricoma presenting as a giant cutaneous horn in an 8-year-old child: A case report and literature review

Pilomatricoma is an uncommon benign adnexal tumor of childhood. We report a case of pilomatricoma presenting as a large, recurrent painful cutaneous horn on the neck of an 8-year-old boy treated with surgical excision. On histopathology, classical features of pilomatricoma along with transepidermal elimination and perforation were shown. We propose that perforating pilomatricoma and pilomatrical horn represent equivalent clinical and pathological entities. The diagnosis of perforating pilomatricoma should be considered in pediatric patients presenting with a cutaneous horn.

Pilomatrical Acanthoma: An Extremely Rare Intraepidermal Variant of Pilomatricoma

ABSTRACT

Pilomatrical differentiation can be observed in a variety of benign and malignant tumors, with the most common prototype being pilomatricoma. Pilomatricoma often presents in the deep dermis or subcutis, and the sole involvement of epidermis is extremely rare. In our current case series, specimens from 5 patients were included with an average age of 68 years. All lesions presented as solitary verrucous or keratotic papules on the extremities, with 1 lesion having a prominent horn. All lesions have a variable mixture of basaloid matrical cells and shadow cells, and all lesions express β-catenin (strong nuclear and cytoplasmic), lymphoid enhancer-binding factor 1 within the matrical component, and pleckstrin homology-like domain family A member 1. The histomorphology and immunoprofile of all lesions are of pilomatrical differentiation, confined to the level of the epidermis. Based on these findings and analogous to the terminology used for other benign intraepidermal proliferations (hidroacanthoma simplex and epidermolytic acanthoma), we propose the term "pilomatrical acanthoma" for these rare lesions.

Giant Pilomatrical Tumor With Broad Epidermal Components: An Example of Histological Diversity and a Potential Diagnostic Pitfall of Tumors With Pilomatrical Differentiation

ABSTRACT

The diagnosis of pilomatricoma, the most common matrical tumor, is generally straightforward; however, it exhibits diverse histology associated with various morphological stages and several clinical variants, and matrical differentiation can occur in various neoplastic diseases. A 56-year-old man was admitted to our hospital to resect an 11.0-cm skin tumor on his right shoulder. Because of its large size and surface irregularities, including multiple erosions and ulcers, cutaneous malignancies were clinically suspected. Histologically, the tumor formed numerous nodules with marked matrical differentiation in the superficial to deep dermis. Although the tumor was macroscopically asymmetrical and irregular, each nodule was microscopically round-shaped and consisted of basaloid cells without marked atypia, atypical mitoses, or lymphovascular invasion. Immunohistochemically, the tumor cells were positive for beta-catenin, LEF-1, and PHLDA-1, consistent with their pilomatrical differentiation. We diagnosed the case as a giant pilomatrical tumor with uncertain malignant potential, considering its "contradictory" features, namely, the worrisome histoarchitecture, such as the asymmetrical silhouette, but bland-looking cytological appearance. Unlike typical pilomatrical tumors, this tumor contained numerous epidermal components with features similar to those of the dermal components, resulting in a unique macroscopic and histological appearance. Our case broadens the known histological diversity of pilomatrical tumors.

Six cases of perforating pilomatricoma: Anetodermic changes with expression of matrix metalloproteinases

Perforating pilomatricoma (PP) is a rare clinical variant of pilomatricoma presenting as a crusted or ulcerated nodule. Previous reports have suggested that the tumor cells perforate the epidermis through a process of transepithelial elimination. Here, we report six cases of PP and examine the mechanism of transepithelial elimination in PP. Histologically, the dermis above or around the tumor nest exhibited edema, dilated vascular spaces, sparse collagen bundles and absence of elastic fibers, suggesting anetodermic changes in all cases. Immunohistochemistry demonstrated many CD68-positive macrophages around the tumor nests. Matrix metallopeptidase (MMP)-9 and MMP-12 were expressed in the inflammatory cells and tumor cells, and were also present in the epidermis and fibroblasts in all cases. We speculate that in PP anetodermic change caused by MMP and elastases including MMP-9 and MMP-12 may precede elimination of the tumor.

Perforating pilomatricoma in a 62-year-old female: a rare case report

Pilomatricoma presents as a single, slow-growing, painless, superficial mass arising from the hair matrix cells, over the hair-bearing areas of the body, especially the head and neck. Perforating pilomatricoma is a rare variant of pilomatricoma presenting as crusted or ulcerated nodule. Here, we report a case of 62-year-old female presenting with rapidly growing noduloulcerative lesion on the left cheek, which on histopathology showed perforating pilomatricoma.

Perforating pilomatricoma with anetodermic epidermis in an adolescent with lymphoma

Pilomatricoma is a benign neoplasm originating from primitive cells of the hair matrix. Occasionally the skin overlying pilomatricomas assumes peculiar clinical features, and anetodermic change of the skin overlying pilomatricomas is sometimes seen, but perforation in pilomatricoma is a rare event. We report a case of perforating pilomatricoma with anetoderma in an adolescent with lymphoma.

Pilomatricomal Horn

We describe a pilomatricomal horn on the right arm of a 39-year-old man. Although initially the tumor was clinically thought to be a verruca vulgaris, the microscopic features were similar to those found in classic pilomatricoma, except for the epidermal location and the presence of a cutaneous horn. Light microscopy showed replacement of the epidermis by basaloid cells, with masses of cornified material containing shadow cells that formed a cutaneous horn. Whereas classic pilomatricoma is confined to the deep reticular dermis or subcutis, the present case represents a unique heretofore unreported epidermal variant of pilomatricoma that pathologists should be aware of to differentiate it from malignant epidermal tumors.

Follicular hybrid cysts with infundibular, isthmic-catagen, and pilomatrical differentiation: a report of 2 patients

The term hybrid cyst was originally coined to describe combination follicular cysts with both epidermoid and trichilemmal (pilar) epithelial zones, separated by an abrupt transition. The concept has since expanded to include many different combinations of pilosebaceous unit differentiation. Entities previously reported also include infundibular and pilomatricomal cyst, trichilemmal and pilomatricomal cyst, eruptive vellus hair cyst combined with steatocystoma or trichilemmal cyst, and trichilemmal, sebaceous, and pilomatricomal cyst. We report 2 cases of follicular hybrid cysts, all mixtures of epidermoid, trichilemmal, and matrical differentiation. The cysts, involving the ear and abdomen, occurred in one woman and one man.

Perforating Pilomatricoma on the Upper Eyelid

We report a rare case of perforating pilomatricoma. A 50 x 40-mm oval nodule, with a whitish scale on its tip, developed on the left upper eyelid of a 43-year-old Japanese woman. There was no history of injury to the left upper eyelid. Histologic examination revealed typical microscopic features of pilomatricoma. In addition, however, an interesting phenomenon was observed: a portion of the tumor mass had extruded from the upper dermis to the skin surface through a perforating epidermal channel in the middle of the tumor. These findings are consistent with the diagnosis of perforating pilomatricoma.

Perforating pilomatricoma in a process of total elimination

Perforating pilomatricoma is a rare clinical variant of pilomatricoma. We report a case of pilomatricoma with ulceration indicating total elimination. The lesion consisted mainly of laminating shadow cells surrounded by invaginating epidermis. We believe that this case can be considered within the category of perforating pilomatricoma.

Perforating follicular hybrid cyst of the tarsus

Follicular hybrid cysts are cutaneous tumors that arise from different portions of the hair follicle. We describe a follicular hybrid cyst of the tarsus that contained features of pilomatricoma and steatocystoma and perforated the palpebral conjunctiva. The unusual location and histopathologic features are discussed.

Perforating pilomatricoma: transepithelial elimination or not

We present a 56-year-old woman with a perforating pilomatricoma in the left eyebrow region. Histologically, the tumor consisted mainly of basophilic cells and shadow cells, and the tumor components were being eliminated through an ulcer with damage to the epithelial structures. In past reports of perforating pilomatricoma, this elimination pattern has often been described as transepithelial elimination. In many patients with perforating pilomatricoma, elimination is accompanied by ulceration and epithelial damage. Mehregan recently stated that elimination accompanied by epidermal necrosis and superficial ulceration constituted one form of transepithelial elimination. Epidermal necrosis and ulceration generally constitute severe damage. However, when Mehregan first proposed the concept of transepithelial elimination, it was defined as a phenomenon with relatively little or no damage to the epithelial structures, differentiating it from other types of elimination. This original definition makes transepithelial elimination a unique and interesting phenomenon, and its most important feature is that there is relatively little or no damage to the epithelial structures. Therefore, the terms "epidermal necrosis" and "ulceration" should not be used in association with transepithelial elimination. Hence, in patients with perforating pilomatricoma, the elimination of tumor components from ulcers with damage to the epithelial structures, as seen in the present case, should not be described as transepithelial elimination.

The first case of exophytic pilomatricoma in an Asian male

Pilomatricomas are benign cutaneous neoplasms that occur frequently in children and usually present as slow-growing, firm, dermal nodules. They are the second most common skin lesion excised from children. A rare exophytic variety has been described, but to our knowledge this has not previously been reported in Asian children. We present this case to highlight the clinical features and to affirm that race may not play a role in the etiology of pilomatricomas. We also illustrate how these lesions can be effectively treated by shave excision.

Pediatric skin tumors

This article summarizes several malignant childhood neoplasms and benign tumors that can mimic malignancies. Because malignant skin tumors are rare in children, parents and physicians often are not sufficiently suspicious to ensure that an early diagnosis can be made. Many malignant skin tumors have features that suggest a vascular or hemangioma-like lesion. Because hemangiomas occur in 10% of infants, it is often considered prudent to adopt a wait-and-see attitude; however, if the lesion is too firm to be a hemangioma or its growth pattern does not follow that of a typical hemangioma, additional options should be considered. To manage childhood skin malignancies, one needs expert consultation, early biopsy, and correct histopathologic interpretation.

A case of eccrine poroma with multiple transepidermal elimination

The skin functions to eliminate foreign substances through the epidermis to the epidermal surface; this process is called transepidermal elimination (TEE). TEE has been observed in various skin tumors. We encountered a 64-year-old male patient with eccrine poroma with marked TEE. A dark brown nodular papule appeared on the anterior aspect of his right leg about 20 years ago and gradually expanded. Histopathologically, cell nests of poroma were extruded to the epidermal surface at several sites. No erosion was noted, and mild to moderate inflammatory cell infiltration was observed in the upper layer of the dermis. According to Mehregan's classification, the TEE, phenomenon observed in our case may correspond to types 2 and 3.

Perforating pilomatricoma

A case of perforating pilomatricoma is described. A few published cases have shared the following features: rapid development, reddish exophytic clinical appearance with surface alterations suggestive of perforation, relatively shallow location making contact with the epidermis, and the occurrence of transepithelial elimination phenomena.