Pilomatrix carcinoma: a clinicopathologic study of six cases and review of the literature

Giant pilomatrix carcinoma of the scalp with intracranial extension: A case report

Key Clinical Message

A very rare skin cancer. Malignant variant of pilomatricoma. It is unique because of its highly aggressive behavior. Responds poorly to chemotherapy and radiotherapy. Treated with a wide surgical excision with safe margins.

Abstract

Pilomatrix carcinoma is uncommon and locally aggressive tumor of the hair follicle matrix. It is a malignant variant of pilomatricoma. If left untreated for a long time may attain massive size and has the potential for distant spread. Only few cases with brain extension have been reported in the literature. Diagnosis of these tumors is established by histopathology. Although pilomatrixoma and pilomatrix carcinoma are well-recognized lesions, clinically they are frequently misdiagnosed as other skin conditions. The tumors respond poorly to chemotherapy and radiotherapy. Thus, recommended treatment is a wide surgical excision with safe margins. Herein, we report the case of a 39-year-old African woman with pilomatrix carcinoma of the scalp eroding the skull bone with intracranial extension.

Atypical Melanocytic Matricoma: A Case Report with Molecular Studies

ABSTRACT

Melanocytic matricoma is a rare benign pilar tumor characterized by matrical differentiation and interspersed dendritic melanocytes. It may show cellular atypia and brisk mitotic activity. Histological characterization of some lesions may be difficult. In addition, because the reported cases are few and have limited follow-up, there is insufficient experience to define outcome-based criteria for malignancy. Some cases of melanocytic matricoma with more prominent atypia have been reported as malignant, but their clinical behavior is uncertain. We present a melanocytic matricoma with interspersed benign dendritic melanocytes, but moderate basaloid atypia, focally brisk mitotic activity, and atypical mitoses. Despite the apparently good delimitation of this tumor, higher magnification revealed a slightly irregular border. However, overt malignant features such as necrosis, frank asymmetry, deep infiltration, and ulceration were not present. This tumor showed a complex aberrant genomic profile with multiple whole chromosomes or chromosomal arms, losses, and duplications. The tumor mutational burden was high. A loss-of-function alteration in CDKN2A and a loss-of-function mutation in TP53 were also present. This unexpected molecular profile contrasts with the relatively bland histology of the tumor and is in line with the difficulties in microscopic differential diagnosis between melanocytic matricoma and an indolent malignant pilomatrical tumor. We suggest that molecular studies and longer follow-up periods may help to further understand and more precisely categorize borderline pilomatrical tumors with melanocytic hyperplasia.

A systematic review of Pilomatrix carcinoma arising from the previous scar site of Pilomatrixoma

Pilomatrix carcinoma is a rare tumor arising from the hair follicle matrix cells most commonly seen in the head and neck region. Also known as "calcified epithelial carcinoma of Melherbe," it was first reported in 1980 by Lopansri and Mihm. Since then till date to the best of our knowledge only around 125 cases were reported in literature, of which only 11 cases were reported to arise from histologically proven areas of previous pilomatrixoma which is the benign variant. One such case is being reported here along with the review of literature. A 50-year-old man presented with a swelling in the nape of his neck since 6 months, which was gradually increasing in size. He had a history of similar swelling at the same site 18 months back for which he underwent a surgery at a center outside. Final histopathology report was suggestive of pilomatrixoma with negative margin. Wide local excision of the tumor with 3 cm margin, placement of surgical clips followed by a primary closure was done. The final histopathology report is suggestive of pilomatrix carcinoma. The patient has no recurrence in 6 months follow-up. The differential diagnosis of pilomatrix carcinoma should be considered in cases of recurrent skin tumors. Wide local excision is the preferred treatment. Re-excision should be done in margin positive cases and cases where simple excision was done due to improper preoperative diagnosis. Due to the rarity of the disease, adjuvant treatment is not properly defined.

Multiple Pilomatricoma in a Middle-Aged Woman

Pilomatricomas are rare skin tumors related to hair follicles. They typically present in children, and the most common locations are head and neck. Pilomatricomas are usually painless; however, they can cause cosmetic problems. Treatment is decided on an individual basis and involves local excision. However, caution should be taken if the lesion is malignant, as resection with safe margins (0.5-1.0 cm) is determinant of the overall outcome. Radiotherapy is indicated in cases of residual tumor tissue or recurrence. The role of chemotherapy in pilomatricomas is still undetermined. We report a 55-year-old female with multiple lumps on her shoulder and back. The sonographic features of these lesions were typically consistent with pilomatricomas. The patient decided to opt for excision due to cosmetic reasons and the histopathology features were suggestive of pilomatricoma.

Vulvar Pilomatrix Carcinoma: Morphologic and Molecular Features

Pilomatrix carcinoma (PC) is a rare malignant variant of pilomatrixoma, a skin adnexal tumor originating from hair matrix cells. It is most often located in the head, neck region, upper back and upper extremities. PC has a locally aggressive behavior but metastasis only occur in 10% of cases. Mutations in CTNNB1, the encoding gene of beta-catenin, have been found in both pilomatrixoma and PC, but other molecular alterations are unknown. The authors present a case of PC in the clitoris, the third known reported case located on the external genitalia. The tumor followed an unusual clinical course with the development of multiple metastases. Next-generation sequencing analysis of the tumor identified, in addition to a characteristic CTNNB1 mutation, pathogenic mutations in PTEN, PIK3CA, and ARID1A, which could explain the aggressive course of the disease. The diagnostic criteria of PC and the differential diagnoses of this unusual tumor in the genital area are discussed.

[Management of malignant adnexal neoplasms of the skin]

Malignant adnexal neoplasms of the skin are a heterogeneous group of rare malignancies with eccrine, apocrine, sebaceous and follicular differentiation. Essential clinical practice recommendations for the overall management of these cancers are presented. Moreover, specific evidence-based findings according to diagnosis, therapy and follow-up of porocarcinoma, sebaceous carcinoma and microcystic adnexcarcinoma will be explained.

Current Diagnosis and Treatment Options for Cutaneous Adnexal Neoplasms with Follicular Differentiation

Neoplasms derived from follicular tissue are extremely rare. Clinically, they are reported as non-symptomatic, slow-growing nodules. These lesions are mainly benign, but the malignant type can occur. Mainly middle-aged people (50-60 years of age) are affected. These carcinomas are mainly localized on the head and neck or torso. They can be locally aggressive and infiltrate surrounding tissue and metastasize to regional lymph nodes. In the minority of cases, distant metastases are diagnosed. Quick and relevant diagnosis is the basis of a treatment for all types of tumors. The patient's life expectancy depends on multiple prognostic factors, including the primary tumor size and its mitotic count. Patients should be referred to a specialized skin cancer center to receive optimal multidisciplinary treatment. This article tries to summarize all the information that is currently available about pathogenesis, diagnosis, and treatment methods of follicular tumors.

Pilomatrixoma with Atypical Features: A Case Report

Pilomatrixoma is an uncommon, benign tumor with differentiation towards both the hair matrix and cells arising in the cortex, most frequently appearing in the first or second decade of life. In rare instances, pilomatrixomas can show malignant transformation. Pilomatrix carcinoma is extremely uncommon and has traditionally been considered a tumor of low malignant potential; however, a high local recurrence rate has been reported. There is a paucity of literature on these lesions, with only a few reports describing the spectrum of malignant changes seen in these lesions. In this case report, we present a case of pilomatrixoma in an adult patient showing atypical features. While the tumor is small, there are focal features that suggest progression to malignancy, but do not fulfill the criteria for pilomatrix carcinoma. These focal atypical features include a focal infiltrative pattern at the periphery, with a variable cytological atypia and an increased mitotic rate, up to five mitotic events/high-power field. Irregular foci of central necrosis (comedonecrosis) were present in several lobules. Some of the features identified were similar to a subset of pilomatrixoma, known as “proliferating pilomatrixoma.” However, our case did not have the diffuse changes or larger size that has been frequently reported in “proliferating pilomatrixoma.” In conclusion, given the lack of focality of the changes, the lesion in our case is best described as a pilomatricoma with atypical features. Furthermore, our case may highlight the need to ensure close clinical follow-up for these lesions with unexpected atypical features that raise concern of recurrence and malignant transformation.

Rare Case Report of Pilomatrical Carcinosarcoma in a Pediatric Patient

We present a case report of the exceptionally rare pilomatrical carcinosarcoma in an even rarer pediatric age group, a 9-year-old female patient. The tumor showed biphasic pilomatrical carcinoma and malignant sarcomatous transformation. To date, the patient is healing well without signs of recurrence. Although limited clinical follow-up is available due to the recent diagnosis, this case may provide a rare look at the clinical outcome of this very rare tumor.

Matrical carcinoma with melanocytic hyperplasia mimicking nodular melanoma in an elderly Mexican male

Matrical carcinoma with melanocytic hyperplasia (MCMH), previously referred to as malignant melanocytic matricoma, is a rare variant of the uncommon pilomatrical carcinoma, occurring most often on the head/neck and upper backs of middle-aged men. Nodular lesions may resemble pigmented basal cell carcinoma or melanoma clinically. We present a case of MCMH in a Hispanic patient with history of melanoma. Histopathological clues to appropriate diagnosis include basaloid cells, numerous atypical mitotic figures, matrical differentiation, shadow cells, strong diffuse nuclear and cytoplasmic expression of ß-catenin, and interspersed pigmented dendritic melanocytes.

Pilomatrical carcinosarcoma of the temple: A case report

Pilomatrical carcinosarcoma is a very rare entity, with only six cases reported until now. This report describes the case of a 100-year-old woman with a mass on the left temple that had existed for several decades but had recently grown in size. Histology showed an asymmetric lesion composed of basaloid cells, spindle cells, and "shadow" or "ghost" cells. Cells had atypical hyperchromatic nuclei with prominent nucleoli, high mitotic activity, and atypical mitosis. In the central area, an epidermal cyst-like structure was seen. The diagnosis of pilomatrical carcinosarcoma was rendered. This case appeared to have arisen from malignant transformation of a pilomatricoma because of the long clinical history and existence of a benign epidermal cyst-like structure. In addition, the observation that the basaloid cells and spindle cells showed a gradual transition from one to the other and that both types were positive for β-catenin would seem to support a common clonal origin for the carcinomatous and sarcomatous components.

Malignant pilomatricoma of the cheek in an infant

Malignant pilomatricoma (pilomatrical carcinoma) is a rare, locally occurring malignant tumor with a high rate of recurrence in the case of incomplete excision. This tumor has two characteristics. First, recurrences of pilomatrical carcinoma are common; second, distant metastasis is rare, but if it occurs, it is very fatal. It has characteristic features of high mitotic counts, cellular atypia, and local invasion. Although fine needle aspiration and excisional biopsy could help to confirm this tumor diagnosis, pathologic findings are critical. Pilomatricomas have some characteristic features in histological aspect, such as epithelial islands of basaloid cells and shadow cells or ghost cell. Also, various types of immunohistochemical staining are used to confirm the diagnosis. Despite the lack of clear surgical criteria, treatment is a wide local excision with histologically clear resection margins with or without adjuvant radiotherapy.

Pilomatrix carcinoma of the right postauricular region: A case report and literature review

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Pilomatrix carcinoma is a very rare locally aggressive tumor.

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A well-defined gold standard for surgical management has not been established.

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Currently wide local excision with safe margins is recommended.

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Regional lymph node dissection is performed when metastasis is suspected.

Introduction

Pilomatrix carcinoma is a rare aggressive tumor with a high rate of local recurrence after surgical excision. Diagnosis is made by histopathology and when discovered, wide local excision has been shown to have the best results.

Presentation of case

We report a case of a 74-year-old male incidentally found to have a large right postauricular mass and regional lymphadenopathy. The mass was biopsied and proven to be a malignant pilomatrixoma. Wide local excision and level II and III neck dissection with reconstruction using a right supraclavicular flap was performed.

Discussion

Pilomatrix carcinoma is a lesion first described in 1880 by Malherbe and Chenantais. It is unknown if these tumors arise de novo or arise through malignant transformation of a benign pilomatrixoma. There are similarities between the benign lesion and its malignant counterpart in terms of activating mutations in signaling pathways. A well-defined gold standard for surgical management has not been established, but currently wide local excision with safe margins is recommended along with regional lymph node dissection when metastasis is suspected. Currently, no chemotherapy regimen has been shown to be effective in local control or in preventing metastatic spread.

Conclusion

Pilomatrix carcinoma, given its aggressive nature, has a high propensity for recurrence after excision. It is important to perform wide local excision to avoid an incomplete resection and higher recurrence rates. Further studies will be needed to create a more defined standard of treatment and to evaluate the role of adjuvant chemotherapy and radiation therapy.

CDX2 and LEF-1 expression in pilomatrical tumors and their utility in the diagnosis of pilomatrical carcinoma

BACKGROUND

The Wnt signaling pathway has been implicated in the pathogenesis of pilomatrical tumors. Lymphoid enhancer-binding factor 1 (LEF-1) is a downstream component of this pathway, and Caudal-related homeobox transcription factor 2 (CDX2) has been postulated to regulate it, but little is known about expression of these transcription factors in pilomatrical tumors.

METHODS

Immunohistochemistry for CDX2, β-catenin, LEF-1, CK19, CK5, Special AT-rich sequence- binding protein 2 (SATB2), cadherin 17 and androgen receptor was performed on pilomatricomas (PMs) (N = 12), pilomatrical carcinomas (PMCAs) (N = 12) and non-pilomatrical cutaneous tumors (N = 18).

RESULTS

PMs and PMCAs were positive for CDX2 (9/12 PMs, sensitivity = 75%, specificity = 100%; 11/12 PMCAs, sensitivity = 92%, specificity = 100%; P < 0.01), β-catenin (12/12 PMs, sensitivity = 100%, specificity = 94%; 10/12 PMCAs, sensitivity = 83%, specificity = 94%; P < 0.01) and LEF-1 (12/12 PMs, sensitivity = 100%, specificity = 56%; 12/12 PMCAs, sensitivity = 100%, specificity = 56%; P < 0.01). CDX2 expression was commonly focal, within a discrete subpopulation of squamoid cells. The LEF-1 expression pattern was different and discernable between pilomatrical tumors (strong, diffuse) and non-pilomatrical tumors (weak, patchy).

CONCLUSION

This study reaffirms the importance of the Wnt signaling pathway in the tumorigenesis of pilomatrical tumors, and this introduces CDX2 as a possible regulator and marker of pilomatrical tumorigenesis. LEF-1 and CDX2 performed at least as well as β-catenin, if not better when taking into account expression pattern, as a diagnostic marker for PMCA, and should be considered in the workup of ambiguous primitive-appearing cutaneous tumors.

Adnexal Carcinomas Treated With Mohs Micrographic Surgery: A Comprehensive Review

BACKGROUND

Adnexal carcinomas (ACs) are rare cutaneous malignancies of sweat gland or pilosebaceous origin. Optimal treatment and metastatic potential of AC are poorly defined. Mohs micrographic surgery (MMS) has been increasingly used to treat AC.

OBJECTIVE

To review selected primary cutaneous AC and their treatment outcomes with MMS.

MATERIALS AND METHODS

Literature review using PubMed search for articles related to primary cutaneous ACs.

RESULTS

Sebaceous carcinoma treated with MMS recurred and metastasized in 6.4% and 3.7%, respectively. Primary cutaneous mucinous carcinoma treated with MMS recurred and metastasized in 9.6% and 6.4%, respectively. After MMS, 4.7% of microcystic AC recurred with no reported metastases. After MMS, recurrences and metastases of trichilemmal carcinoma or hidradenocarcinoma have not been reported. Two (4.2%) regional lymph node metastases but no distant metastases or local recurrences have been reported in eccrine porocarcinoma. Squamoid eccrine duct tumor, pilomatrix carcinoma, and spiradenocarcinoma treated with MMS are also reviewed.

CONCLUSION

The rarity of ACs and the lack of comparative data on treatment makes conclusive recommendations on treatment difficult. Recent large case series and reviews suggest MMS is a useful and possibly superior treatment for AC and should be considered if primary cutaneous disease is suspected.

Treatment of Malignant Cutaneous Adnexal Neoplasms

Malignant cutaneous adnexal neoplasms form a group of rare, typically low-grade-malignancy carcinomas with follicular, sebaceous, apocrine, or eccrine differentiation or a combination of the first 3 subtypes. Their clinical presentation is usually unremarkable, and biopsy is required to establish the differentiation subtype and the definitive diagnosis. Due to their rarity, no clear consensus has been reached on which treatment is most effective. Mohs micrographic surgery is considered to be the best option to prevent recurrence in the majority of patients. Radiotherapy and chemotherapy have been studied in very few cases and have rarely been shown to be effective.

Malignant Pilomatricoma: A Report of Two Cases and Review of Literature

Malignant pilomatricoma is an extremely rare tumour arising from the hair follicle. About 80 known cases are reported in literature till date. Presented herewith are two cases of malignant pilomatricoma, occurring in young female patients, each with a different clinical presentation and outcome. It is important to be aware of this entity as malignant pilomatricoma, though, initially locally aggressive, can recur if incompletely excised and also can metastasize to lungs, bones and lymph nodes.

Giant Pilomatrix Carcinoma of the Face

This case report describes an unusually large facial pilomatrix carcinoma (PC) in a 60-year-old man. This PC had been growing slowly for 11 months and had recently ulcerated. It measured 9 cm × 7 cm × 5 cm. Initial punch biopsy findings were inconclusive. The tumor was excised in total with 5-mm margins in a supra-superficial musculoaponeurotic system plane. The defect was reconstructed with a cervicofacial bilobed rotational advancement flap. Histopathologic findings confirmed the diagnosis of PC. There was no lymph node spread or distant metastasis. The patient recovered with a good esthetic result. This case represents one of the largest facial PCs reported in the literature. Diagnostic challenges are discussed, and the literature is reviewed.

Basal Cell Carcinoma With Matrical Differentiation: Clinicopathologic, Immunohistochemical, and Molecular Biological Study of 22 Cases

Basal cell carcinoma (BCC) with matrical differentiation is a fairly rare neoplasm, with about 30 cases documented mainly as isolated case reports. We studied a series of this neoplasm, including cases with an atypical matrical component, a hitherto unreported feature. Lesions coded as BCC with matrical differentiation were reviewed; 22 cases were included. Immunohistochemical studies were performed using antibodies against BerEp4, β-catenin, and epithelial membrane antigen (EMA). Molecular genetic studies using Ion AmpliSeq Cancer Hotspot Panel v2 by massively parallel sequencing on Ion Torrent PGM were performed in 2 cases with an atypical matrical component (1 was previously subjected to microdissection to sample the matrical and BCC areas separately). There were 13 male and 9 female patients, ranging in age from 41 to 89 years. Microscopically, all lesions manifested at least 2 components, a BCC area (follicular germinative differentiation) and areas with matrical differentiation. A BCC component dominated in 14 cases, whereas a matrical component dominated in 4 cases. Matrical differentiation was recognized as matrical/supramatrical cells (n=21), shadow cells (n=21), bright red trichohyaline granules (n=18), and blue-gray corneocytes (n=18). In 2 cases, matrical areas manifested cytologic atypia, and a third case exhibited an infiltrative growth pattern, with the tumor metastasizing to a lymph node. BerEP4 labeled the follicular germinative cells, whereas it was markedly reduced or negative in matrical areas. The reverse pattern was seen with β-catenin. EMA was negative in BCC areas but stained a proportion of matrical/supramatrical cells. Genetic studies revealed mutations of the following genes: CTNNB1, KIT, CDKN2A, TP53, SMAD4, ERBB4, and PTCH1, with some differences between the matrical and BCC components. It is concluded that matrical differentiation in BCC in most cases occurs as multiple foci. Rare neoplasms manifest atypia in the matrical areas. Immunohistochemical analysis for BerEP4, EMA, and β-catenin can be helpful in limited biopsy specimens. From a molecular biological prospective, BCC and matrical components appear to share some of the gene mutations but have differences in others, but this observation must be validated in a large series.

Pilomatrix carcinoma: More malignant biological behavior than was considered in the past

Pilomatrix carcinoma is a very rare malignancy, with ~130 cases reported in the literature. In the past, pilomatrix carcinoma was considered to be a low-grade malignant tumor. Currently, however, its significant recurrence and metastatic potential has been well documented. Lymph node and systemic metastases are frequently observed. Wide surgical excision of the primary lesion is the principal modality of treatment, whereas adjuvant radiotherapy may be beneficial in local tumor control. Lymph node metastases may be treated surgically or with radiotherapy. Systemic disease is not responsive to chemotherapy, and is hence associated with a poor prognosis. Since the majority of nodal and systemic metastases present after the initial diagnosis and treatment, follow-up examinations of these patients may be warranted, despite the currently inadequate treatment options. In the present study, a case of pilomatrix carcinoma of the parotid region with early local recurrence only 2 months after complete excision with negative surgical margins is reported. The local recurrence was treated by excision and radiotherapy. The associated literature is also discussed.

Malignant Melanocytic Matricoma: A Report of 2 Cases and Review of the Literature

BACKGROUND

To describe 2 cases of melanocytic matricoma with malignant histological features and systematically review previously reported cases of malignant melanocytic matricoma.

METHODS

Two cases of malignant melanocytic matricoma were identified from the practice of the authors. Additional 3 cases were identified in the literature. The clinical and pathological features of these 5 cases are described.

RESULTS

Malignant melanocytic matricoma occurs predominantly in sun-damaged skin of elderly individuals. The tumor is composed of atypical epithelial cells with brisk mitotic activity showing evidence of matrical keratinization and widespread positivity with beta-catenin. There is an admixed cytologically bland dendritic melanocytic component. To date, local recurrence has occurred in one case, but no cases of disseminated disease or death have been reported.

CONCLUSIONS

Recognition of this rare tumor and separation from a range of diagnostic mimics is important to ensure adequate treatment by local excision and to allow further cases to be identified to better define the biological potential of this lesion.

Giant proliferating pilomatricoma; report of a rare entity

Proliferating pilomatricoma is a benign tumour and a rare variant of pilomatricoma that has the potential for local recurrence if incompletely excised. We report a case of giant proliferating pilomatricoma on the forearm of a 66-year-old woman. This tumour was unusually large and the presence of ulceration and rapid growth raised clinical suspicion of malignancy. The identification of shadow or ghost cells is a good clue to matrical differentiation, which can be confirmed by β-catenin immunostaining.

Pilomatrix carcinoma of the vulva

Background

Pilomatrix carcinomas are rare, frequently occurring in older male patients. We report a case of vulvar pilomatrix carcinoma in a 30-year-old woman, the second known reported case occurring on the external genitalia.

Case

A 30-year-old female originally presented at an outside institution for the management of an asymptomatic vulvar mass that was biopsied and read as invasive squamous cell carcinoma. Pathology review at our institution reclassified the vulvar mass as a low-grade pilomatrix carcinoma. The patient underwent radical hemivulvectomy without an inguinal–femoral groin node dissection. She has remained without evidence of disease recurrence for more than 5 years since her diagnosis.

Conclusion

Pilomatrix carcinoma can be confused for an invasive squamous cell carcinoma. Due to its low risk of metastases, a less radical surgical approach can be taken. Consideration of this unusual malignancy is important in the determination of appropriate management.

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We present a rare case of vulvar pilomatrix carcinoma in a 30 year old female.

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Pilomatrix carcinoma can be confused for an invasive squamous-cell carcinoma.

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Due to its low risk of metastases, a less radical surgical approach can be taken.

Basal cell carcinomas showing histological features generally associated with cutaneous adnexal neoplasms

Basal cell carcinoma (BCC) is the commonest malignant neoplasm in humans. Although a histopathological diagnosis of BCC is straightforward in the vast majority of cases, unusual histological variants can present a diagnostic challenge. A small proportion of BCCs show features which are generally associated with cutaneous adnexal neoplasms. Such changes may involve either the epithelium or the stroma and can mislead the pathologist particularly in small biopsies. Despite the growing evidence which speculate that BCC is a primitive follicular tumor, it is unusual to encounter tumors which actually show definitive signs of adnexal differentiation. This review aims to address this somewhat overlooked aspect of a very common tumor and offers practical guidance to distinguish them from adnexal neoplasms which they might mimic.

Matrical Carcinoma With Melanocytic Proliferation and Prominent Squamoid Whorls

Matrical carcinoma (pilomatrix carcinoma) is a rare follicular low-grade malignancy with matrical differentiation. A pigmented variant with admixed dendritic melanocytes is exceedingly rare with only 7 cases reported in the literature. The diagnosis of malignancy can be difficult to establish. The authors report a case of a 79-year-old woman with a matrical carcinoma who presented with an ulcerated nodule on the posterior right leg, measuring 2.2 cm in greatest dimension. The excisional biopsy showed irregularly shaped dermal and subcutaneous nodules ranging in size from 0.1 to 0.5 cm. The nodules were composed of aggregates of large atypical basaloid cells, with multiple, sometimes atypical, mitoses, admixed with ghost cells, and central necrosis en masse. In addition, the neoplasm was characterized by focal marked melanocytic proliferation and multiple whorls of pink eosinophilic material reminiscent of keratin pearls (squamoid whorls). The basaloid cells were positive for beta-catenin both in the nuclei and the cytoplasm and negative for BerEp4. S100, Melan-A, and HMB45 highlighted the melanocytic dendritic cells. Pan-cytokeratin was negative in the ghost cells and focally positive in the squamoid whorls. Squamoid whorls seem to be a significant feature of matrical carcinoma.

Pilomatrix carcinoma on the left side of the parotid region: A case report and review of the literature

Pilomatrix carcinoma (PC) is a rare neoplasm, particularly in the parotid region. Thus, it is easily misdiagnosed and an optimal treatment regimen has not yet been established. The present study reports the case of a 43-year-old female who presented with a PC of the parotid region and reviews the associated published literature. The patient underwent three surgical excisions prior to the tumor being completely removed, and was misdiagnosed four times prior to the correct diagnosis. Once the tumor was completely removed, the patient received radiation therapy (RT). At the 2-year follow-up, the patient remained free of local recurrence and metastasis. To the best of our knowledge, only 3 cases of PC on the parotid region have been reported. Although an optimal treatment regimen has not been established, surgery with wide margins is recommended, with RT and chemotherapy producing mixed results.

Molecular pathology of skin neoplasms of the head and neck

CONTEXT

Skin neoplasms include the most common malignancies affecting humans. Many show an ultraviolet (UV)-induced pathogenesis and often affect the head and neck region.

OBJECTIVE

To review literature on cutaneous neoplasms that show a predilection for the head and neck region and that are associated with molecular alterations.

DATA SOURCES

Literature review.

CONCLUSIONS

Common nonmelanoma skin cancers, such as basal and squamous cell carcinomas, show a UV-induced pathogenesis. Basal cell carcinomas are characterized by molecular alterations of the Hedgehog pathway, affecting patched and smoothened genes. While squamous cell carcinomas show UV-induced mutations in several genes, driver mutations are only beginning to be identified. In addition, certain adnexal neoplasms also predominantly affect the head and neck region and show interesting, recently discovered molecular abnormalities, or are associated with hereditary conditions whose molecular genetic pathogenesis is well understood. Furthermore, recent advances have led to an increased understanding of the molecular pathogenesis of melanoma. Certain melanoma subtypes, such as lentigo maligna melanoma and desmoplastic melanoma, which are more often seen on the chronically sun-damaged skin of the head and neck, show differences in their molecular signature when compared to the other more common subtypes, such as superficial spreading melanoma, which are more prone to occur at sites with acute intermittent sun damage. In summary, molecular alterations in cutaneous neoplasms of the head and neck are often related to UV exposure. Their molecular footprint often reflects the histologic tumor type, and familiarity with these changes will be increasingly necessary for diagnostic and therapeutic considerations.

Pilomatrix carcinoma: 13 new cases and review of the literature with emphasis on predictors of metastasis

BACKGROUND

Pilomatrix carcinoma is a rare cutaneous tumor derived from follicular matrix cells with few cases documented in the literature.

OBJECTIVE

We sought to better characterize this tumor by analyzing its epidemiologic, clinical, and histopathologic features in 13 new cases and by reviewing the literature.

METHODS

All cases of pilomatrix carcinoma from a large regional dermatopathology practice were identified and analyzed by chart review for clinical and histopathologic characteristics. Similar characteristics were compiled from an additional 123 cases in the English-language literature. Cox proportional hazards regression models were used to determine risk factors associated with the development of metastasis for all identified metastatic tumors.

RESULTS

Our 13 tumors were most common in middle-aged to older white men and presented mostly on the head/neck. Histopathologically, tumors were asymmetric, were poorly circumscribed, were composed of basaloid and "ghost" cells, had frequent atypical mitoses, and had infrequent lymphovascular invasion. Wide excision was considered the most definitive treatment modality, but local recurrence was common. When analyzing all reported cases of metastasis using statistics, metastasis was significantly associated (hazard ratio 3.45, P < .0413) with local tumor recurrence.

LIMITATIONS

The retrospective, single-center design and the reliance on electronic medical records are limitations.

CONCLUSIONS

This study helps better characterize pilomatrix carcinoma and identifies potential predictors of metastasis.

Skin tumors with matrical differentiation: lessons from hair keratins, beta-catenin and PHLDA-1 expression

BACKGROUND

Pilomatricomas are tumors that emulate the differentiation of matrix cells of the hair follicle, showing cortical differentiation, with sequential expression of K35 and K31 keratins. Beta-catenin gene is frequently mutated in pilomatricoma, leading to beta-catenin nuclear accumulation, and to downstream expression of LEF1. Skin matrical tumors other than pilomatricoma are very rare, and comprise purely matrical tumors and focally matrical tumors. We aimed at studying cortical differentiation, beta-catenin pathway and expression of the follicular stem-cell marker PHLDA1 in a series of matrical tumors other than pilomatricoma.

METHODS

In 36 prospectively collected tumors, K31, K35, CK17, LEF1, HOXC13, beta-catenin and PHLDA1 expressions were evaluated. Five pilomatricomas were used as controls.

RESULTS

In 18 purely matrical tumors (11 matrical carcinomas, 4 melanocytic matricomas, 3 matricomas) and 18 focally matrical tumors (11 basal cell carcinomas, 3 trichoepithelioma/trichoblastomas, 4 others), sequential K35, HOXC13 and K31 expressions were found, indicating cortical differentiation. Germinative matrix cells were always CK17-, and showed nuclear beta-catenin accumulation, with LEF1 and PHLDA1 expressions.

CONCLUSIONS

Nuclear beta-catenin and LEF1 expression was highly conserved in matrical tumors, and suggested a common tumorigenesis driven by Wnt pathway activation. PHLDA1 was consistently expressed in matrical tumors and in areas of matrical differentiation.

Pilomatrix carcinoma: a case report and review of the literature

Pilomatrixoma is a common benign neoplasm of children and young adults with a female predilection. In contrast, its malignant counterpart, pilomatrix carcinoma is a rare neoplasm of older adults with a male preponderance. Pilomatrix carcinomas are locally aggressive with a tendency to recur. We report a case of a 44-year-old male who presented with an enlarging soft tissue tumor on the right upper back. Histology revealed an asymmetric, poorly circumscribed, lobulated neoplasm located deeply in the dermis with infiltration into the underlying subcutaneous tissue. The tumor was comprised of basaloid cells containing vesicular nuclei, prominent nucleoli, scant cytoplasm, and brisk mitotic activity. A focus of basaloid cells transitioning to shadow cells with central keratinized material and tumor necrosis was also present. The diagnosis of a pilomatrix carcinoma was rendered. Considering the infiltrative nature of this neoplasm with perineural and intramuscular invasion, the patient underwent 3 surgical excisions before it was completely removed.

Agminated pigmented matricoma: a case of a unique tumor with a multifocal appearance composed of neoplastic matrical cells with a significant component of melanocyte

Matricoma is benign follicular neoplasm with the same constituent cells as pilomatricoma but with a different silhouette. Matricoma consists mostly of solid aggregations of matrical cells, as opposed to pilomatricoma, which is often a cystic lesion. We herein describe a case of agminated pigmented matricoma. A 27-year-old Japanese man visited our hospital complaining of three separate, pigmented, firm and sessile nodules on the back. Histopathologic examination revealed mostly solid aggregations of matrical and supramatrical cells located mainly within the dermis and the upper part of the subcutis. Shadow cells were present mostly within the aggregations. At higher magnifications, occasional indication of inner sheath differentiation, in addition to differentiation toward hair in the form of shadow cells, could be discerned in the center of the aggregations. The matrical and supramatrical cells within the aggregations were relatively uniform in size and shape, and contained several mitotic figures. Heavily pigmented melanocytes were present within the aggregations of matrical and supramatrical cells, and heavily pigmented melanophages were found in adjacent stroma. Pigmentation is a rare event in benign and malignant adnexal tumors, and to our knowledge, no similar case has been reported.

Characterizing pilomatricomas in children: a single institution experience

BACKGROUND/PURPOSE

Pilomatricomas, or calcifying epitheliomas of Malherbe, are among the most common superficial cutaneous soft tissue lesions in children. Familiarity with the presenting signs and symptoms allows for the diagnosis to be made on physical examination alone in most patients, avoiding expensive and unnecessary diagnostic imaging.

METHODS

A retrospective IRB-approved review of surgical pathology archives and medical records of all patients undergoing excision of pilomatricomas between 1982 and 2010 was performed to determine the characteristics of the pilomatricoma tumors. Data regarding gender, age, location, size of tumor, and histopathology were collected.

RESULTS

There were 916 pilomatricomas resected in 802 patients. Fifty-five percent of the patients were girls (441 patients). The median age at the time of resection was 6 years (range 5 months to 18 years). Multiple lesions were found in 43 patients (5%). The most common location was head and neck (n = 529, 58%), followed by upper limbs (n = 214, 23%), trunk (n = 130, 14%), and lower limbs (n = 43, 5%). Information on size was available for 674 lesions; mean lesion diameter was 14.0 ± 7.4 mm. Twenty-eight patients (3%) had either recurrent (n = 11) or metachronous (n = 17) lesions resected at our institution, with a median interval of 12 months after initial resection (range 5 weeks to 5 years). No cases of pilomatrix carcinoma were observed.

CONCLUSION

The majority of pilomatricomas occur in the head and neck, although they can present in any location. Approximately 5% of children have multiple lesions. Pilomatricomas occur slightly more commonly in girls, and 66% of lesions occur in children < 10 years of age. Complete surgical excision is necessary to prevent recurrence. Recurrences and pilomatrix carcinoma are very rare if complete excision is achieved.

Pilomatricoma of the breast in an adolescent girl: sonographic findings

I report a case of pilomatricoma of the breast in an adolescent girl. Sonograms showed a solitary circumscribed, oval, heterogeneously hyperechoic mass in the skin. This is the first description of sonographic findings for this rare tumor in an adolescent breast.

A 5-year-old girl with an enlarging mass at the elbow

Pilomatrixoma is a rare benign neoplasm that presents as a solitary, hard, mobile, subcutaneous mass. Pilomatrixomas can be found on any hair-bearing region of the body, with the upper extremity being the second most common location. Pilomatrixomas are common in children, and have a higher frequency in girls. We present a case of left-arm pilomatrixoma in a 5-year-old girl. Surgical excision was curative. Pediatric orthopedic surgeons should be familiar with this benign tumor when evaluating a calcified soft-tissue mass in the extremities of a child.