Trichoblastic carcinoma ("malignant trichoblastoma") with lymphatic and hematogenous metastases

Trichoblastic Carcinoma in the Glabella Treated With Mohs Micrographic Surgery

Trichoblastic carcinoma (TBC) is a rare adnexal neoplasm of follicular germ cell differentiation with the potential for local invasion and metastasis. Histologic features of trichoblastic carcinoma have significant overlap with trichoblastoma and basal cell carcinoma (BCC), making diagnosis difficult in some cases. Treatment strategies are not well defined and include surgical excision for localized tumors and systemic therapies for metastatic disease. We present a case of trichoblastic carcinoma clinically resembling a benign cyst that was ultimately treated with Mohs micrographic surgery (MMS).

Trichoblastic carcinosarcoma of the neck: Case report and molecular analysis of a seldom, relapsing entity and a review of the literature

Trichoblastic carcinosarcoma is a seldom biphasic adnexal tumor with malignant epithelial and mesenchymal components. The authors report the first tumor on the neck developed from preexistent trichoblastoma showing aggressive, recurrent behavior. An 82-year-old man presented with a solitary 3-cm exophytic lesion. Histology verified the diagnosis of trichoblastic carcinosarcoma. Four years earlier, a trichoblastic carcinoma arising in a preexisting trichoblastoma was excised at the same location. Despite successful surgical treatments, three local recurrences within 4 years were diagnosed. After the second relapse, the patient agreed on adjuvant radiation. Twelve months later, another relapse was excised in toto. In the last surgical specimen, only the mesenchymal component was found. Copy number variation analysis of the preexisting tumor and two recurrences revealed the same entity and additional chromosomal aberrations in the recurrences. Adnexal carcinosarcomas are seldom, yet presumably underdiagnosed biphasic tumors with aggressive growth potential. They should have adequate preoperative clarification with wide tumor excision, as radiosensitivity seems to be of limited effect.

Safety and efficacy of the anti-PD1 immunotherapy with nivolumab in trichoblastic carcinomas

Trichoblastic carcinoma is a rare malignant cutaneous adnexal tumor with a risk of local invasion and distant metastasis. As of today, there is no consensus for the treatment of locally advanced or metastatic trichoblastic carcinoma. "AcSé Nivolumab" is a multi-center Phase II basket clinical trial (NCT03012581) evaluating the safety and efficacy of nivolumab in several cohorts of rare, advanced cancers. Here we report the results of nivolumab in patients with trichoblastic carcinoma. Of the eleven patients enrolled in the study, five patients had been previously treated by sonic hedgehog inhibitors. The primary endpoint 12-week objective response rate was 9.1% (N = 1/11) with 1 partial response. Six patients who progressed under previous lines of treatment showed stable disease at 12 weeks, reflecting a good control of the disease with nivolumab. Furthermore, 54.5% of the patients (N = 6/11) had their disease under control at 6 months. The 1-year overall survival was 80%, and the median progression-free survival was 8.4 months (95%CI, 5.7 to NA). With 2 responders (2 complete responses), the best response rate to nivolumab at any time was 18.2% (95%CI, 2.3-51.8%). No new safety signals were identified, and adverse events observed herein were previously described and well known with nivolumab monotherapy. These results are promising, suggesting that nivolumab might be an option for patients with advanced trichoblastic carcinomas. Further studies on larger cohorts are necessary to confirm these results and define the role of nivolumab in the treatment of trichoblastic carcinomas.

Extremely Rare Pulmonary Metastases of Skin Basal Cell Carcinoma: Report of Two Cases with Clinicopathological Features

Basal cell carcinoma (BCC) is the most frequent human skin cancer, but metastasizing BCC (MBCC) is extremely rare, developing in approximately 0.0028% to 0.55% of BCC patients. Herein, we report two cases of pulmonary MBCC. The first one developed in a 72-year-old male who underwent surgical resection due to multiple recurrences and adjuvant radiotherapy. Immunohistochemistry showed that neoplastic cells expressed Ber-EP4, CK5/6, p63, EMA (focally), BCL-2, and CD10, but were negative for CK7, CK20, S100, estrogen and progesterone receptors, and TTF-1. The second case is a 64-year-old female treated with vismodegib. Clinicopathological features and differential diagnoses are described.

A case of racemiform trichoblastoma in a dog

Trichoblastoma, which is common in dogs, is now occurring with other cellular changes outside the recognized forms to warrant their continuous evaluation for proper elucidation even as their causes largely remain unknown. A case at hand involved a 9-year-old Caucasian dog, which weighed 35 kg with chief complaint of a progressive bleeding mass on the scalp. The dog had an up-to-date vaccination record and all vital parameters were within optimum ranges. The surgical excision of the firm, solitary, and alopecic mass with traumatized upper surface revealed the presence of a well-demarcated and unencapsulated mass composed of grapes-like nests of basaloid epithelial cells within follicular stroma devoid of stromal necrosis, inflammatory cellular infiltration, and neoplastic epidermal connection. However, there was tissue necrosis, hemorrhages, and inflammatory cellular infiltrates on the exposed upper part of the traumatized growth. Immunohistochemical analysis showed positive reactivity to AE1/AE3, CK5/6, and p63 but negative immunoreactivity to CK7, CK20, CEA, and TTF-1. The histomorphological and immunohistochemical evaluation of the mass on the scalp of the dog suggested a solitary racemiform trichoblastoma with a traumatized exposed upper part despite basal cell carcinoma mimicry where histological diagnosis currently hold sway over immunohistochemical evaluation.

Trichoblastic carcinoma: a comprehensive review of the literature

Trichoblastic carcinoma is a rare neoplasm thought to arise from malignant degeneration of benign follicular tumors. Its clinical features, optimal treatment, and outcomes remain largely unknown. We performed a comprehensive review of the existing trichoblastic carcinoma literature. PubMed and Google Scholar were searched for keywords related to trichoblastic carcinoma, and additional articles were found in reference lists. Cases with a histopathologic diagnosis of trichoblastic carcinoma were summarized. A total of 93 cases have been described, all in case reports or case series. The average age was 65, with 66.7% of cases in males. A minority of patients had familial tumor syndromes or a history of radiation at the site, and only one was reported to be immunosuppressed. The most common site was the face (48.4%), and the majority developed de novo (87.1%). The clinical presentation was highly variable. Although most cases (82.8%) were successfully treated with surgery alone, a subset of patients had more aggressive disease including local progression or recurrence in five cases, nodal metastases in five cases, and distant metastases in three cases. Trichoblastic carcinoma is a rare malignancy with the potential for aggressive behavior. Further research is needed to better characterize this neoplasm.

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.

Morphologically high-grade trichoblastic carcinoma: a clinicopathological study with long-term clinical follow-up

AIMS

Trichoblastic carcinomas (malignant trichoblastomas) are rare and poorly documented neoplasms characterised by malignant transformation of a pre-existing benign trichoblastoma, and are subdivided histologically into low-grade and high-grade tumours. Whereas morphologically low-grade trichoblastic carcinomas show indolent behaviour, morphologically high-grade trichoblastic carcinomas have been associated with a poor prognosis, but little is known about their true biological potential. The aim of this study was to better define the clinicopathological features and outcomes of morphologically high-grade trichoblastic carcinomas.

METHODS AND RESULTS

Four high-grade trichoblastic carcinomas were retrieved from departmental files, and the clinical and histopathological features and follow-up were recorded. The tumours presented as nodules on the scalps, necks and shoulders of adults (median age, 40 years; range, 30-55 years) with a female predominance of 3:1. Three patients had a longstanding history with recent change. Histologically, three tumours were characterised by an expansile cellular nodule composed of sheets of pleomorphic epithelioid cells with brisk mitotic activity and necrosis arising in a background of a benign trichoblastoma. One tumour showed a more gradual transition from a benign trichoepithelioma to an undifferentiated carcinoma with infiltrative growth and perineural infiltration. All patients were alive with no evidence of recurrence or metastasis following complete excision after a median follow-up of 96 months (range, 30-180 months).

CONCLUSIONS

The correct diagnosis of high-grade trichoblastic carcinoma relies on adequate sampling and recognition of the benign trichoblastic precursor lesion, i.e. trichoblastoma or trichoepithelioma. Despite the concerning histological features of the malignant component, the tumours appear to be less aggressive than previously thought.

Trichoblastic carcinosarcoma in a 34-year-old woman with histopathologic and molecular analysis, including re-demonstration of a CDKN2A p.(R58*) mutation

Trichoblastic carcinosarcomas are rare, adnexal-type cutaneous carcinosarcomas that are thought to be related histogenetically to trichoblastomas, yet in which both the epithelial and stromal components show features of malignancy. Ten cases have been described in the literature thus far, with a predilection for the head and neck of older males. We present a case of cutaneous carcinosarcoma in sun-damaged skin of a 34-year-old woman showing features of a trichoblastic carcinosarcoma, with histopathologic analysis along with targeted next-generation sequencing of 50 cancer-associated genes. Two pathogenic variants in TP53 were identified, p.(R158C), p.(R273P), along with a likely pathogenic variant CDKN2A, p.(R58*). In particular, it is noted that the CDKN2A p.(R58*) missense mutation has been described in two previous cases of cutaneous carcinosarcomas, including a case of trichoblastic carcinosarcoma.

Trichoblastomas Mimicking Basal Cell Carcinoma: The Importance of Identification and Differentiation

Trichoblastoma is a rare, slow-growing, benign cutaneous tumor derived from follicular germinative cells. Trichoblastoma commonly appears as an asymptomatic, symmetrical, well-circumscribed, skin-colored to brown or blue-black papule or nodule. It may appear clinically and histologically similar to basal cell carcinoma, making its diagnosis challenging. Even on dermoscopy, it is challenging to differentiate trichoblastoma from basal cell carcinoma. In practice, it is important to differentiate the two, because the choice of treatment and resulting prognosis differ between the lesions. Surgical biopsy to analyze histopathological and immunohistochemical differences is the gold standard for diagnosing and differentiating trichoblastoma from basal cell carcinoma. Trichoblastoma typically has a favorable prognosis, with a low incidence of recurrence, progression or association with malignancy. This paper provides a review of the epidemiology, clinical presentation, dermoscopy, histology, immunochemistry, treatment, and prognosis of trichoblastoma.

18F-FDG PET/CT Imaging of Trichoblastic Carcinoma With Nodal Metastasis

Trichoblastic carcinoma is an uncommon malignant neoplasm arising from follicular germinative cells. The high-grade trichoblastic carcinoma has been reported with lymphatic and hematogenous dissemination. The authors present a 59-year-old man with gluteal cleft trichoblastic carcinoma and highlight the useful role of serial F-FDG PET/CT examinations in the demonstration of initial and subsequent nodal metastasis in the inguina and pelvis.

Histological Features and Treatment Approach of Trichoblastic Carcinomas: From a Case Report to a Review of the Literature

Background

Trichoblastic carcinoma (or malignant trichoblastoma) is a rare malignant cancer of adnexal structures with morphological features that in some cases are reminiscent of a trichoblastoma. Trichoblastic carcinoma is underdiagnosed as it is a rather recent entity which is still not recognized as such by all pathologists. The differential diagnosis with basal cell carcinoma is often difficult to make and the optimal treatment has not yet been established.

Case report

We report the case of a 43-year-old patient who underwent surgical excision and adjuvant radiotherapy for a growing mass of 40 × 48 mm located in the lumbar right paraspinal skin. The pathological findings demonstrated a trichoblastic carcinoma. The clinicopathological profile, the histogenesis, and the difficulties related to the histopathological diagnosis and treatment of this rare entity are discussed in this article.

Conclusion

Although the published reports on this disease are few, surgery should be considered the standard therapeutic approach for trichoblastic carcinomas. Selected cases presenting clinical features of local aggressiveness can safely be treated with adjuvant irradiation to improve local control. However, acute and particularly late toxicities need to be taken into account in the decision.

[Why is it important to differentiate trichoblastic carcinomas (CT) from basal cell carcinomas (CBC). About 21 cases]

Trichoblastic carcinoma is a rare epithelial malignant epithelial tumor, its diagnosis is difficult and the therapeutic management is non-consensual. This retrospective study, carried out between 2009 and 2015, covered 21 cases and analyzed the diagnostic and therapeutic characteristics of trichoblastic carcinomas. Sex ratio is 2. Trichoblastic carcinoma predominated in the face (65% of cases), particularly in perinasal (30% of cases). Its clinical presentation is in 95% of cases as basal cell carcinoma, which is the first clinical diagnosis evoked. The average size of the tumors was 2.3cm in diameter (from 0.7cm to 15cm). The treatment of these tumors is surgical: the margins retained were on average 0.7cm (0.5cm to 1cm). The first excision was mostly performed under local anesthesia, healthy borders were found in less than 40% of cases, requiring another intervention under general anesthesia with reconstruction by flap or skin graft in nearly 80% of cases. The lymph node metastasis rate was 5%. Three cases of recurrence (17%) occurred between 18 months and 6 years follow-up, despite complete resection. One case recurred three times. These results highlight the difficulty of diagnosing trichoblastic carcinomas, often confused with basal cell carcinomas. Though larger, poorly limited and infiltrating, trichoblastic carcinomas are not really distinguished from basal cell carcinomas. Only the anatomopathological examination of the excision piece make it possible to conclude, the biopsy being most often insufficient. Their local aggressiveness requires a greater margin of excision. The micrographic analysis of Mohs, for the periorificial lesions of the face, would reduce margins, increase their reliability and limit the number of surgical revisions. Finally, the literature reports a high rate of ganglion and visceral metastases (between 9.5 and 11%). Initial search for distal lymph node or metastatic involvement is essential, as well as regular clinical follow-up.

Folliculosebaceous neoplasms: A review of clinical and histological features

Numerous benign and occasionally malignant tumors arise from the folliculosebaceous apparatus. Confusing terminology, rarity of malignant variants and overlapping histological features can lead to diagnostic uncertainty. This review highlights the clinical and histopathological features that help to classify these entities, as well as the various syndromes associated with certain members of this large family of tumors.

Twelve Years' Observation of Multiple Familial Trichoepithelioma with Squamous Carcinoma

Long-standing trichoepithelioma lesion on scalp with 12 years follow-up. The patient was observed for 12 years, and the carcinoma recurred 3 times during 8 years after surgical excision and radiation therapy. Malignant transformation may occur in multiple familial trichoepitheliomas; Moderate radiation therapy should be given for malignant transformation patients with lower radiation dose and shorter time. Removing the trichoepithelioma as soon as possible if the tumor suddenly or continuously increased is recommended.

Trichoblastic carcinosarcoma: an authentic cutaneous carcinosarcoma

We describe a trichoblastic carcinosarcoma on the forehead of a 65-year-old man. This is the fifth case of trichoblastic carcinosarcoma in the literature and the first to be reported from the USA. It was successfully treated with direct excision. Trichoblastic carcinosarcoma should be distinguished from epidermal carcinosarcoma. We believe trichoblastic carcinosarcoma is an authentic carcinosarcoma derived from multiple progenitor cells whereas epidermal carcinosarcomas are derived from a single progenitor cell that undergoes epithelial to mesenchymal transition, and are better considered as sarcomatoid carcinomas.

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.

Multiple trichoblastomas in a dog

BACKGROUND

Hair follicle tumours generally present as benign, solitary masses and have a good prognosis following surgical resection.

HYPOTHESIS/OBJECTIVES

This report describes a case of multiple trichoblastomas in a dog.

ANIMAL

A 2-year-old crossbred dog presented with multiple soft cutaneous periocular, perilabial, submandibular and nasal nodules, between 2 and 9 cm in diameter, located on the right side of the face. New nodules were observed on the same side of the face at a second consultation 3 weeks later.

METHODS

Surgical resection of all nodules was performed in two procedures. Three nodules were initially resected and submitted for histolopathology and immunohistochemistry. The diagnosis was trichoblastoma for all three. At the time of the second consultation, new and remaining nodules were biopsied and the diagnosis of trichoblastoma confirmed. The dog was treated with doxorubicin and piroxicam for 30 days prior to the second surgical procedure in an attempt to reduce new tumour growth and the size of present tumours. All nodules were resected and the defects closed using rotation flaps.

RESULTS

No recurrence of the neoplasm was noted within 10 months after surgery.

CONCLUSIONS AND CLINICAL IMPORTANCE

Trichoblastomas are generally benign but can present as multiple neoplasms that may require surgical resection and may respond to chemotherapy. To the authors' knowledge, this is the first report of multiple trichoblastomas in a dog.

A collision tumour consisting of malignant trichoblastoma and melanosarcoma in a rabbit

A 7-year-old mixed breed neutered female rabbit (Orytolagus cuniculus) developed a solitary black nodular mass (1 cm in diameter) in the skin of the right flank. Microscopically, the mass consisted of an admixture of neoplastic trichoblasts and melanocytes. The former were arranged as solid, trabecular, island-like and gland-like structures and the cells had oval nuclei with prominent nucleoli and lightly eosinophilic scant cytoplasm. The latter population exhibited prominent nuclear atypia and high mitotic index in the clusters of a few cells or single cells. Immunohistochemically, the neoplastic trichoblasts expressed cytokeratins and E-cadherin, while the neoplastic melanocytes expressed vimentin, S100 protein, melan-A and melanoma antigen. A diagnosis of collision tumour involving malignant trichoblastoma and melanosarcoma was made.

[Trichoblastic carcinoma]

INTRODUCTION

Trichoblastic carcinoma is a rare malignant adnexal tumor. Its presentation is non-specific and the diagnosis is always histological.

CASE REPORT

A 56-year-old patient presented with a trichoblastic carcinoma of the eyelid and eyebrow. It was located on the lower end of the scar, 7 years after the incomplete excision of a tumor. There was a large subcutaneous extension of the tumor, well beyond the visible margins of the skin lesion. The treatment was a broad surgical excision followed by radiotherapy. There was neither local recurrence nor metastasis 20 months later.

DISCUSSION

This clinical presentation was atypical and had never been reported. We discuss the therapeutic management of this rare tumor.

Sunitinib efficacy in the treatment of metastatic skin adnexal carcinomas: report of two patients with hidradenocarcinoma and trichoblastic carcinoma

BACKGROUND

Adnexal carcinomas are rare and diverse cutaneous tumours. They are locally aggressive and have the potential for distant metastasis. Metastatic adnexal carcinomas are very resistant to conventional chemotherapies. Sunitinib, an oral tyrosine kinase inhibitor, is reportedly effective for the treatment of various solid cancers. Its use in adnexal carcinomas has never been reported.

OBSERVATIONS

The first patient had metastatic clear cell hidradenocarcinoma and was stabilized over 8 months with sunitinib, before she relapsed. The second patient had a metastatic malignant hair follicle tumour (trichoblastic carcinoma) and achieved a partial remission with sunitinib, and disease stabilized after 10 months. Dynamic contrast-enhanced ultrasound (DCE-US) performed to evaluate tumour vascularization during treatment depicted a dramatic and early decrease in the tumour blood volume.

CONCLUSIONS

Sunitinib was effective in controlling the disease in our two patients. DCE-US using linear raw data may have an early predictive value for tumour response to sunitinib. Further studies involving larger cohorts of patients are warranted in order to confirm the efficacy of sunitinib in these rare tumours.

Low-dose X-ray depilatory treatment induces trichoblastic tumors of the scalp

BACKGROUND

Depilatory radiotherapy for ringworm was largely used before antifungals were available. Patients who underwent this treatment are at high risk of developing scalp tumors or other cancers. The aim of this study was to characterize scalp tumors occurring after X-ray therapy for ringworm.

METHODS

We included cases of postradiotherapy scalp tumors recorded at the Dermatology Department of the Charles Nicolle Hospital, Tunis between 1988 and 2001. We recorded clinical descriptions and all cases were resubmitted to microscopic analysis.

RESULTS

Sixty-one tumors occurred in 33 men and 12 women with a mean age of 49.8 years. Radiodermatitis was present in 21% of patients. Tumors were basal cell carcinomas in 47 cases, trichoblastomas in 10 cases and trichoblastic carcinomas in 4 cases. Twelve patients had 2-5 tumors, with combinations of tumor types in 3 of them. Mean delay of onset of tumors after radiotherapy was 39.4 years in basal cell carcinoma cases, 38.3 years in trichoblastoma cases and 35.6 years in trichoblastic carcinoma cases.

CONCLUSIONS

This series shows that although basal cell carcinoma is the most frequent tumor in this situation, trichoblastomas are common. We describe, for the first time, radio-induced trichoblastic carcinomas. Trichoblastic tumors have not yet been described in this context because this concept is relatively recent.

PTCH mutations are not mainly involved in the pathogenesis of sporadic trichoblastomas

Trichoblastomas are rare, benign tumors of the appendix in human skin. The histopathology comprises elements of basal cell carcinoma and trichoepithelioma with a variable degree of follicular differentiation. Both basal cell carcinoma and trichoepithelioma reveal alterations of PTCH, the human homolog of the Drosophila segment polarity patched gene. Furthermore, heterozygous PTCH knockout mice develop trichoblastoma-like tumors. This suggests an involvement of the PTCH gene in the pathogenesis of human trichoblastomas. However, trichoblastomas arising in nevus sebaceus did not show loss of heterozygosity at the PTCH locus (9q22.3) in a previous study. Sequencing of the PTCH gene and analysis of sporadic human trichoblastomas have not been performed yet. We therefore screened 10 sporadic trichoblastomas and 1 trichoblastoma arising within a nevus sebaceus for PTCH mutations. After microdissection of the tumors, single-strand conformational polymorphism (SSCP)/heteroduplex analysis of exons 2 to 23 of PTCH was performed, and polymerase chain reaction products with aberrant band patterns were sequenced. One trichoblastoma revealed a silent mutation at codon 562 in exon 12. Another trichoblastoma showed a somatic C > T single nucleotide substitution at codon 1,315 (exon 23), which was not present in corresponding normal epidermis. This mutation at codon 1,315 represents an already described PTCH germline polymorphism and results in a heterozygous Pro to Leu substitution in the tumor. The Pro/Leu polymorphism in germline is associated with a higher risk for breast cancer, but a potential contribution to the tumorigenesis of trichoblastoma is unknown. We detected no classical PTCH mutations in the investigated trichoblastomas. Our results indicate that PTCH mutations are not mainly involved in the pathogenesis of sporadic trichoblastomas, in contrast to basal cell carcinomas and trichoepitheliomas. The genetic basis of this rare appendageal tumor remains elusive.

Trichoblastic sarcoma: a high-grade stromal tumor arising in trichoblastoma

We report a case of primary sarcoma of the skin with a biphasic histological pattern, being composed of areas of mixed mesenchymal-epithelial cell proliferation and areas of purely sarcomatous growth. The tumor occurred in the posterior cervical region of a 93-year-old man, and its history was marked by sudden, rapid enlargement after many years of stable duration. The excised lesion was about 4 cm in diameter, had a firm consistency and was covered by intact skin. Histological examination showed a multifocal proliferation of follicular germinative cells arranged in corymbiform and petaloid shapes with an overall retiform growth pattern. Epithelial cords and strands were composed of cytologically uniform cells with bland nuclear features and were surrounded by a prominent, fibroblast-rich stroma reminiscent of a perifollicular sheath. In many areas of the tumor the stroma showed abrupt transition into a pleomorphic proliferation of large sarcomatous cells with frequent and often atypical mitoses. Multinucleated neoplastic cells infiltrated the epithelial structures to cause their partial or total obliteration in many fields of the lesion. Immunohistochemically, the epithelial cells displayed expression of various keratins, with a particularly intense staining for 34betaE12, and were partly positive for the CD10 antigen. A strong immunostaining for this antigen was also observed in malignant-appearing stromal areas, where no expression of cytokeratins was detected. Moreover, nuclear positivity for p53 protein was seen in sarcomatous cells, whereas it resulted in total lack of epithelial elements. Our case emphasizes that high-grade sarcoma may occur in the spectrum of trichoblastic tumors and that it may share some features of other noncutaneous biphasic neoplasms, such as mammary cystosarcoma phyllodes.

Skin adnexal neoplasms--part 1: an approach to tumours of the pilosebaceous unit

Skin adnexal neoplasms comprise a wide spectrum of benign and malignant tumours that exhibit morphological differentiation towards one or more types of adnexal structures found in normal skin. Most adnexal neoplasms are relatively uncommonly encountered in routine practice, and pathologists can recognise a limited number of frequently encountered tumours. In this review, the first of two, the normal histology of the skin adnexal structures is reviewed, and the histological features of selected but important benign and malignant tumours and tumour-like lesions of pilosebaceous origin discussed, with emphasis on the diagnostic approach and pitfalls in histological diagnosis.

Malignant Melanocytic Trichoblastoma

Trichoblastoma is an uncommon benign cutaneous neoplasm of the hair germ cell. The pigmented variety of the tumor is rare. There have only been a few case reports describing the malignant counterpart of trichoblastoma. There are no reports describing a pigmented variety of malignant trichoblastoma. We are presenting a case report of a 47-year-old patient with malignant trichoblastoma containing melanin deposits and propose to define this variety of the tumor as a separate entity: malignant melanocytic trichoblastoma.

High-grade trichoblastic carcinoma arising in trichoblastoma: a rare adnexal neoplasm often showing metastatic spread

It has been debated whether malignant transformation of trichoblastoma occurs. The concept was recently forwarded that basal cell carcinoma is as a malignant neoplasm of follicular germinative cells and should be named trichoblastic carcinoma to show its relationship to trichoblastoma. Almost all basal cell carcinomas are low-grade malignant neoplasms and develop metastases only very rarely, and if so, only after very long duration and untreated growth. Only rare basal cell carcinomas arise in trichoblastomas. Up to now there have only been two reports of high-grade trichoblastic carcinoma arising in trichoblastoma, showing systemic metastatic spread and death. We add two further cases of trichoblastic carcinoma with anaplastic nuclei, arising in trichoblastoma. One of the tumors arose in a small nodular trichoblastoma on the right forearm of an 84-year-old male patient. The other one was a trichoblastic carcinoma at the base of a trichoepithelioma on the right thigh of an 87-year-old woman with Brooke-Spiegler syndrome. Our cases emphasize that high-grade trichoblastic carcinoma develops via malignant transformation of trichoblastoma, and is very rare.

Malignant transformation within benign adnexal skin tumours

AIMS

To report five malignant trichogenic tumours arising in longstanding, previously benign adnexal neoplasms through malignant transformation. Malignant trichogenic adnexal tumours are extremely rare neoplasms.

METHODS AND RESULTS

The patients were between 55 years and 79 years of age. Three of the tumours were located on the arms, two on the face. Three of our patients had a history of chronic lymphocytic leukaemia, one patient had a history of colonic adenocarcinoma. The duration of the tumour nodules was reported as between 20 and 40 years before sudden changes occurred. These changes included rapid growth, pain, itching, ulceration and bleeding. Histologically, all tumours were well circumscribed and encapsulated. There was a residual benign tumour component and morphological signs such as bone formation, dystrophic calcification and sclerosis suggesting long duration of the lesions. All patients except for one, who refused further clinical investigation due to her advanced age of 79 years, had an underlying systemic malignancy.

CONCLUSIONS

The growth stimulus in these benign adnexal neoplasms resulting in malignant transformation may be attributed to the acquisition of additional genetic events or to immunosuppression due to an underlying neoplastic disease. Therefore, patients with systemic diseases or malignancy should be carefully examined and followed for sudden changes in pre-existing benign cutaneous tumours.

Trichoblastic neoplasm with apocrine differentiation

Trichoblastoma is a benign neoplasm with primitive hair follicle differentiation. The tumor is characterized by nests and cords of epithelial cells in an organized relation to stroma. The epithelial cells differentiate toward follicular germ and follicular sheath. More divergent differentiation in the form of sebaceous elements in trichoblastoma has infrequently been reported in the literature. We report a trichoblastic neoplasm showing typical features of trichoblastoma as well as areas of apocrine differentiation. The neoplasm, which was present for several months, was removed from the chin of a 31-year-old woman. Histologic examination showed a neoplasm composed of basaloid nests with occasional papillary mesenchymal bodies as well as ducts and glands exhibiting apocrine differentiation. Trichoblastoma with apocrine features is rarely reported in the literature.

Tricholemmal carcinoma in continuity with trichoblastoma within nevus sebaceus

A nodule arising within the nevus sebaceus on the vertex of the scalp of a 68-year-old woman was histopathologically and immunohistochemically investigated. We also used immunohistochemistry to investigate the cytokeratin (CK) distribution of the outer root sheaths of normal terminal hair follicles. The nodule consisted of two parts, a main exophytic part with a lobular proliferation and a small peripheral part with the features of trichoblastoma. The main exophytic lesion consisted of lobular aggregations composed of both or either basaloid cells and clear cells with the silhouette and cytology of malignancy. The columnar clear cells were aligned in a palisade at the periphery of the aggregations of clear cells, and the aggregations located in the superficial dermis were connected to the follicular infundibular structures. Almost all of the neoplastic aggregations were diffusely positive for CK7 (OV/TLR/30), and the innermost or inner cells of the neoplastic aggregations were positive for CK17; a similar staining pattern to that in the lower portion of the outer root sheath between the A and B fringes in normal terminal hair follicles. The exophytic part of the lesion was a malignant neoplasm with differentiation mainly toward the lower segment of the outer sheath between the A and B fringes of the terminal hair follicle, namely tricholemmal carcinoma. Our case may represent a collision of two distinctive neoplasms (tricholemmal carcinoma and trichoblastoma), however, an intimate relationship between these two neoplasms also should be considered.