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

Adnexal neoplasms of the eye

Adnexal neoplasms of the eyelid encompass a wide variety of benign and malignant tumors of sebaceous, follicular, and sweat gland origin. Due to the specialized structures of the eyelid, these neoplasms present differently when compared with those of other locations. Although most dermatologists and ophthalmologists are familiar with the commonly reported adnexal tumors of the eyelid, such as hidrocystoma, pilomatrixoma, and sebaceous carcinoma, many other adnexal neoplasms have been reported at this unique anatomic site. Accurate and timely identification of these neoplasms is essential, as alterations of eyelid anatomy and function can have a negative impact on eye health, vision, and quality of life. We review the clinical and histopathologic features of common and rare eyelid adnexal neoplasms and discuss proposed treatment options.

Case report: Pilomatrix carcinoma with PDL1 expression and CDKN2A aberrant

Case report

A 55-year-old male patient developed a mass in the left inguinal area with left lower limb swelling and first visited a local hospital 3 months earlier because of unrelieved pain. An MRI scan suggested left suprapubic branch and left acetabular bone destruction, abnormal soft tissue signals within the iliopsoas muscle of the anterior edge of the left iliac bone, and enlarged lymph nodes in the left iliac fossa and left inguinal region. The patient subsequently underwent left pelvic lesion open biopsy and inguinal lymph node resection biopsy. According to pathological reports, the left inguinal mass was considered to be a malignant tumor of cutaneous accessory origin (pilomatrix carcinoma) with extensive vitreous changes. The suprapupubis branch mass was considered to be a bone metastatic pilomatrix carcinoma. Immunohistochemistry (IHC) revealed a PDL1 combined positive score (CPS) of 8. DNA next-generation sequencing (NGS) showed CDKN2A L65Rfs*53 mutation. The patient received three cycles of gemcitabine and nedaplatin. However, the lesion progressed.

Conclusion

Chemotherapy is not effective for treating pilomatrix carcinoma. PDL1 antibodies and CDK4/6 inhibitors might be treatment options for pilomatrix carcinoma.

Pilomatrix carcinoma of the lower extremity: A rare case report and literature review

INTRODUCTION

Pilomatrix carcinoma (PC) is a rare skin malignancy of the hair follicles matrix that tends to be locally aggressive with 10-16 % risk of metastasis mostly to the pulmonary and lymphatic system. There are no clear protocols for the management of PCs, however surgical intervention with clear margins has been highly considered in PC management to decrease risk of recurrence.

CASE PRESENTATION

A 40 year-old male patient presented to our clinic to evaluate an asymptomatic, slow-growing nodule localized on his left thigh. A CT scan revealed a well-defined, enhanced lesion with microcalcification. "En bloc" surgical resection of the lesion was performed and histopathology confirmed the diagnosis of pilomatrix carcinoma.

CLINICAL DISCUSSION

Given its rarity, there are no definitive guidelines regarding PC treatment. However, surgical intervention with clear margins including wide local excision or Mohs micrographic surgery has been highly considered. In our case, wide excision of the lesion with clear margins was performed with no evidence of recurrence one year later.

CONCLUSION

Given the local aggressive nature of PC, appropriate surgical intervention is essential in decreasing the risk of recurrence. Wide excision with clear margins has been proposed to decrease the risk of recurrence. Additionally, total-body skin examination should be done 2-3 times annually to evaluate for recurrence or metastasis.

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 comparative study of pilomatricoma and epidermoid cyst with ultrasound

AIM

To explore and compare the ultrasonic (US) features of pilomatricoma (PM) and epidermoid cyst (EC) in the differential diagnosis and improve the accuracy of US diagnosis of PM.

MATERIALS AND METHODS

Three hundred and nine patients who underwent US examination before surgery with a histopathological diagnosis of PM or EC after surgery were analysed retrospectively. The patients were categorised into the training and validation sets according to the inspection times. Univariate analysis was undertaken on the US and clinical features of PM and statistically significant variables (p<0.05) were included in the multivariate logistic regression model to establish a diagnostic model.

RESULTS

The results demonstrated that the multivariate logistic regression model for PM was statistically significant (p<0.001). The risk factors included posterior echo attenuation and hypoechoic halos (odds ratio [OR] = 9.277, 10.254) and the protective factors included age, diameter thickness, and posterior echo enhancement (OR=0.936, 0.302, 0.156). The performance of the diagnostic model was tested using the training set (area under the receiver operating characteristic curve [AUC] = 0.974, 95% confidence interval [CI] = 0.955-0.994) and the validation set (AUC = 0.967, 95% CI = 0.926-1.000), which demonstrated good discriminant ability.

CONCLUSIONS

The diagnostic accuracy for PM was higher than that for EC when the nodule is characterised by posterior echo attenuation, hypoechoic halos, smaller thickness, and younger age. The US diagnostic model developed may be used to guide the diagnosis of PM.

Giant Pilomatrix Carcinoma of the Thorax: An Uncommon and Clinically Misdiagnosed Tumor

Pilomatrix carcinoma is an unusual and aggressive malignant tumor deriving from follicular matrix cells and exhibiting a metastatic potential to lungs and regional lymph nodes in 10% of cases. We report the case of a 54-year-old male patient who presented with a biopsy-proven malignant pilomatrixoma of the thoracic region, which recurred multiple times after previous excisions. Due to the size of the tumor (28 by 22 cm), wide excision and axillary lymphadenectomy of levels I and II were performed, followed by reconstruction with a free deep inferior epigastric artery perforator flap and adjuvant radiotherapy. Owing to its rarity, this tumor can initially be misdiagnosed, resulting in delayed treatment and recurrences if inadequately excised. Also, large tumor size is correlated with a higher incidence of metastasis. High index of clinical suspicion and wide excision are recommended, along with the need of establishing oncological guidelines for better prognosis.

An enlarging nodule on the vertex of scalp in an elderly man

A 79-year-old man presented with a crusty yellow lesion on his scalp. Histological examination revealed ulceration of the epidermis with an underlying mass in the dermis. Immunohistochemistry showed positivity for p63, and focal positivity for AE1/AE3, CK5/6 and EMA.

Pilomatrix Carcinoma: Report of Two Cases of the Head and Review of the Literature

BACKGROUND

Pilomatrix carcinoma (PC) is a rare skin tumor arising from hair follicle matrix cells. It is locally aggressive with a high rate of local recurrence after surgical excision. Few cases in the literature have been described and the management is not well defined.

OBJECTIVES

The aim of this study was to present two cases of PC located on the head and review the relevant literature about epidemiology, clinical and dermoscopic evaluation, characteristics of local and distant metastases, local recurrence rate and management of this rare skin tumor.

METHODS

We consulted databases from PubMed, Research Gate and Google Scholar, from January 2012 to November 2022. We reviewed the literature and reported two additional cases.

RESULTS

We selected 52 tumors in middle-aged to older patients located mostly on the head. Dermoscopy evaluation was rarely performed in the pre-operative diagnostic setting. The most definitive treatment was wide local excision, but local recurrences were common. In total, we observed 11 cases of recurrences and 9 patients with locoregional or distant metastases. Four patients received adjuvant radiotherapy, two patients needed chemotherapy and local cancer therapy and one patient received radiochemotherapy.

CONCLUSION

Our reports and the review of the literature can provide a better awareness and management of this rare tumor.

Melanocytic matricoma with atypical features: A case of malignant melanocytic matricoma?

Melanocytic matricoma is a rarely reported, benign cutaneous adnexal neoplasm composed of epithelial cells exhibiting differentiation towards hair matrix as well as admixed, pigmented, dendritic melanocytes. The proposed malignant counterpart to melanocytic matricoma, malignant melanocytic matricoma (MMM), is even more rare. Here we report a case of a melanocytic matricoma with atypical features in a 92-year-old female with a 1.2-cm pigmented nodule on the right nasal sidewall. Histopathology revealed a well-circumscribed dermal tumor composed of atypical matrical cells with scattered aggregates of anucleate keratinocytes (ghost cells), prominent intratumoral pigment, numerous mitotic figures (88 mitosis/10 high-power field [HPF]), and intermixed dendritic melanocytes. A literature review was performed for MMM to determine if the current case fit diagnostic criteria for this entity. Including the current case, 12 cases of MMM were identified and analyzed to investigate common clinical and histopathologic features. MMM commonly occurred on the head and neck (7/12 cases) of older individuals (median age of 80) with a slight male predominance (male-to-female ratio of 3:1) and on histopathology presented as a multinodular dermal tumor composed of mitotically active (average mitotic rate of >50 mitoses/10 HPF) pleomorphic epithelial cells with foci of ghost cells. Dendritic melanocytes were found throughout the tumor lobules in all cases. Given that only two of 12 cases have exhibited locally aggressive behavior, further study is warranted to determine the true malignant potential of MMM.

Malignant proliferating trichilemmal tumor of the scalp: report of 4 cases and a short review of the literature

Malignant proliferating pilar tumors are very rare adnexial lesions that can be confused with other skin neoplasms. The authors present four patients with malignant proliferating trichilemmal tumors located on the scalp. A review of the literature search for malignant proliferating pilar tumors and treatments was performed.

Malignant Pilomatricoma of the Lower Extremity: A Difficult and Rare Diagnosis

Malignant pilomatricoma is a rare cutaneous malignancy that is commonly found on the head and neck. We present a patient with malignant pilomatricoma of the lower extremity with intralesional calcification and giant cells, confirmed by histopathology. This patient’s case represents a clinically important variation of malignant pilomatricoma in an uncommon anatomical location.

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.

Ultra-high-frequency ultrasound of superficial and musculoskeletal structures in the pediatric population

Because of its relatively low cost, lack of ionizing radiation and great versatility, US is considered the imaging modality of choice to evaluate a large variety of pediatric conditions. Imaging of superficial structures and small anatomical parts can be at times limited with standard US. Recent advances in technology yielded ultra-high-frequency US systems that are capable of scanning with frequencies as high as 70 MHz and resolutions of 30 μm. This technology, approved by the United States Food and Drug Administration, has not been widely used in the clinical setting. It has the potential to become a powerful diagnostic tool in clinical practice, especially in the evaluation of infants, given their inherent body habitus. Our main objective is to discuss the use of ultra-high-frequency US at a tertiary care center. This pictorial essay presents a gamut of pediatric pathologies pertaining to imaging of the soft tissues and the superficial and musculoskeletal structures. Our aim in this pictorial essay is to highlight and illustrate the role of ultra-high-frequency US in improving the depiction of common and less common pathologies. We think it also helps to gain a new understanding of the normal anatomy in the pediatric population and to display specific features not shown by standard US and, in certain cases, ones that lead to a change in diagnosis.

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.

Comparison of Benign and Malignant Pilomatricomas Using Whole-exome Sequencing

BACKGROUND

Malignant pilomatricoma (MP) is a rare cancer of the hair matrix with only a few cases reported in literature. Given the rarity of this cancer and the lack of relevant genetic data, very little is known about the nature of the molecular pathophysiology except the involvement of the Catenin Beta 1 (CTNNB1)/Wnt/β-catenin signaling pathway in some cases.

MATERIALS AND METHODS

We describe the whole-exome genomic profiling of four samples from two patients: 1) an MP from patient I, 2) a coexisting benign pilomatricoma (BP) from patient I, 3) a BP from an age and location-matched control patient II, and 4) normal skin tissue from patient II.

RESULTS

We detected a pathogenic somatic missense mutation in fibroblast growth factor receptor 4 (FGFR4) (c.1162G>A, p. Gly388Arg) in MP and coexisting BP in patient I, whereas the control BP harbored the classical CTNNB1 mutant.

CONCLUSION

This study, the first comparative analysis of benign and MP through whole-exome analysis, identified a novel oncogenic mutation in FGFR4.

[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.

Pilomatrical Tumor of Low Malignant Potential: A Tumor Between Pilomatricoma and Pilomatrical Carcinoma

ABSTRACT

We report a case of pilomatrical tumor showing intermediate histological features between pilomatricoma and pilomatrical carcinoma. The lesion recurred twice with the same histological features. Similar cases were was probably called aggressive or proliferating pilomatixoma; we think that the term pilomatrical tumor of low malignant potential is more suitable for this lesions. Excision with wide free margins and follow-up are recommended.

18F-FDG PET/CT Findings in Metastatic Pilomatrix Carcinoma

We describe a rare case of metastatic pilomatrix carcinoma with distant metastases 10 months after diagnosis. A 37-year-old woman was diagnosed with pilomatrix carcinoma by excisional biopsy from the occipital region and referred to us for F-FDG PET/CT examinations at the time of diagnosis and 10 months after diagnosis. The first PET/CT did not show any pathological activity, whereas the second PET/CT showed multiple intensive F-FDG uptakes in the right lung parenchyma, right hemithorax pleura, liver, and bones.

Pilomatrix Carcinoma of the Antecubitum

We present the case of a 46-year-old male with atypically large left elbow pilomatrix carcinoma present for 10 years with emergent excision after developing life-threatening hemorrhage. Pilomatrix carcinoma is a dermal-based malignant tumor typically of the head and neck region. Histopathology shows islands of basaloid cells, shadow cells, and fibromyxoid fibroma. Reoccurrence is seen in 23% of cases on an average of six months after primary excision. The current standard of care is wide excision with close follow-up.

An Overview of Uncommon Cutaneous Malignancies, Including Skin Appendageal (Adnexal) Tumours and Sarcomas

A standardised classification of malignant skin appendageal (adnexal) tumours and sarcomas is required for improved patient management and prognosis. This has been hindered by considerable morphological variation both within and between tumour types, the use of many synonyms for the same tumour types and variation in classification between pathologists. This update uses the improved classification in the 2018 WHO classification of skin tumours as the basis to discuss malignant skin appendageal tumours, sarcomas and cutaneous metastases that regularly present to skin cancer clinicians, multidisciplinary skin cancer teams and tumour boards, with current evidence for management, where appropriate.

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.

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.

Pilomatrix Carcinoma Masquerading as Breast Carcinoma

Pilomatrix carcinoma is an exceedingly rare skin adnexal neoplasm derived from piliferous follicles, usually occurring in the head and neck region. Localization of this tumor in the breast is a rarity. We now report an unusual case of a 49-year-old female who presented with a palpable mass in the left breast for 2 years. Mammogram revealed a large, lobulated opacity with calcification, and positron emission tomography–computed tomography showed a metabolically active soft tissue mass measuring 15 cm involving all the quadrants of the left breast. Subsequently, the patient underwent radical mastectomy, and histopathologic diagnosis of pilomatrix carcinoma of the breast was offered. Pilomatrix carcinoma, although exceedingly rare, can have an intramammary location and can be misdiagnosed as breast carcinoma on limited material. A high index of suspicion is required to arrive at an accurate diagnosis so as to obviate neoadjuvant chemotherapy.

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.

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.

Benign follicular tumors

Benign follicular tumors comprise a large and heterogeneous group of neoplasms that share a common histogenesis and display morphological features resembling one or several portions of the normal hair follicle, or recapitulate part of its embryological development. Most cases present it as clinically nondescript single lesions and essentially of dermatological relevance. Occasionally, however, these lesions be multiple and represent a cutaneous marker of complex syndromes associated with an increased risk of visceral neoplasms. In this article, the authors present the microscopic structure of the normal hair follicle as a basis to understand the type and level of differentiation of the various follicular tumors. The main clinicopathological features and differential diagnosis of benign follicular tumors are then discussed, including dilated pore of Winer, pilar sheath acanthoma, trichoadenoma, trichilemmoma, infundibuloma, proliferating trichilemmal cyst/tumor, trichoblastoma and its variants, pilomatricoma, trichodiscoma/fibrofolliculoma, neurofollicular hamartoma and trichofolliculoma. In addition, the main syndromes presenting with multiple follicular tumors are also discussed, namely Cowden, Birt-Hogg-Dubé, Rombo and Bazex-Dupré-Christol syndromes, as well as multiple tumors of follicular infundibulum (infundibulomatosis) and multiple trichoepitheliomas. Although the diagnosis of follicular tumors relies on histological examination, we highlight the importance of their knowledge for the clinician, especially when in presence of patients with multiple lesions that may be the cutaneous marker of a cancer-prone syndrome. The dermatologist is therefore in a privileged position to recognize these lesions, which is extremely important to provide further propedeutic, appropriate referral and genetic counseling for these patients.

Concurrent Pilomatrix Carcinoma and Diffuse Large B-Cell Lymphoma

Pilomatrix carcinoma is a rare cutaneous tumor derived from follicular matrix cells. It may arise de novo or from a malignant transformation of a pilomatrixoma. The latter process has been associated with impaired immune system surveillance of the host caused by UV radiation or the onset of an underlying malignant neoplasm. We report a case of a 58-year-old man presenting with a long-standing pilomatrix carcinoma on the inner right leg after 10 years of repeated curettage of the lesion, concurrent with a high-grade B-cell lymphoma on the same extremity. We describe a rare association which highlights the necessity of close follow-up of patients with long-standing malignant skin tumors.

Malignant hair follicle tumors of the periorbital region: A review of literature and suggestion of a management guideline

Malignant hair follicle tumors are rare skin adnexal malignancies that have a predilection for the head and neck region. They can be categorized into a number of different subtypes. Histologically, they are distinct from their benign counterpart. To the best of our knowledge, there is no extensive review of these malignancies, especially in the periorbital region. We aim to provide a literature review and a guideline for management of these malignant tumors in the periorbital region. Database from Medline, PubMed, Embase, and Google Scholar were consulted. A total of 16 cases from the literature on hair follicle malignancies in the periorbital region were included in this review. The clinical presentations, diagnostic patterns, investigations used, and best management approach of these tumors are discussed. The American Joint Committee on Cancer (AJCC) 7(th) edition carcinoma of the eyelid staging system was used to describe their behaviors. We recommend wide excision surgery and a close follow-up for these tumors. Tumors presenting with a late stage require work-up for distant metastasis and consideration for exenteration procedures. The role of radiotherapy and chemotherapy in this context is still uncertain.

Giant pilomatrixoma presenting in the posterior thorax, a rare location and the largest described

Pilomatrixoma is a common benign soft tissue neoplasm arising from hair follicle cells, typically not exceeding 3 cm and located mainly within the head and neck regions. Lesions greater than 3 cm or those located elsewhere are rare and are often not thought of or high on a differential diagnosis. Moreover, the radiographic features of pilomatrixoma are very nonspecific making the diagnosis even more difficult and rarely described in the radiology literature. We present the largest reported case of pilomatrixoma measuring 24 cm arising from the posterior thorax. Our hope is to increase awareness of this diagnosis for slow-growing soft tissue masses not located in the classically described locations of head and neck, explore the radiographic features on various imaging modalities, and review the current radiology literature.