Malignant proliferating trichilemmal tumours: an histopathological and immunohistochemical study of three cases with DNA ploidy and morphometric evaluation

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 Proliferating Trichilemmal Tumor of the Scalp: A Systematic Review

OBJECTIVES

Malignant proliferating trichilemmal tumors of the scalp can exhibit aggressive presentation and recurrences. Our objective was to perform an evidence-based systematic review evaluating clinical presentation, tumor characteristics, and treatment modalities used to determine which treatment strategies had the best outcomes.

METHODS

The databases PubMed, Embase, and Cochrane Library were searched for relevant literature by the authors. Patient demographics, imaging, treatments, and other clinical characteristics were obtained. The results were reported using the Preferred Reporting Systems for Systematic Reviews and Meta-Analysis guidelines.

RESULTS

Thirty-nine studies with a total of 65 patients were identified. The most common presentation was a history of slow-growing, painless swollen mass on the scalp. In total, 10 patients (15.4%) presented with spread to the regional lymph nodes and 6 (9.2%) additional patients presented with metastasis to distant locations. In total, 61 patients (93.8%) underwent surgery. Various chemotherapy and radiation therapy regimens were used. Of the 45 cases with documented follow-up, 11 (24.4%) patients had one or multiple instances of local, lymph node or metastatic tumor recurrence.

CONCLUSIONS

Surgery is favored, and the exact approach should be based on clinical judgment. However, Mohs micrographic surgery should strongly be considered because of its superior margin control against such an invasive tumor. Radiotherapy and chemotherapy have been used as adjuvant therapy in aggressive cases or recurrence. Patients should be followed closely and examined often to frequently assess recurrence or metastasis. Randomized controlled trials are needed to further clarify these findings.

Malignant Proliferating Trichilemmal Tumor: A Subtle Presentation in an African American Woman and Review of Immunohistochemical Markers for This Rare Condition

A malignant proliferating trichilemmal tumor (MPTT) is thought to represent the malignant counterpart of a benign proliferating trichilemmal cyst, a keratin-filled lesion that derives from the outer hair root sheath. The clinical appearance of MPTTs does not always correlate with their histopathologic behavior, emphasizing the need for biopsy and histopathological analysis. Here, we present a 46-year-old African American woman who was evaluated for an ostensibly benign cyst on her scalp that was diagnosed as an MPTT following histopathological examination. She was treated with simple surgical resection that was flush with the cyst margins, followed by Mohs surgery to ensure complete resection. As immunohistochemistry (IHC) has often been used to characterize MPTTs, we also review the various IHC markers reported in the literature.

TP53 Abnormalities and MMR Preservation in 5 Cases of Proliferating Trichilemmal Tumours

Proliferating trichilemmal tumours (PTT) are defined by a benign squamous cell proliferation inside a trichilemmal cystic (TC) cavity. A possible explanation of this proliferative phenomenon within the cyst may be molecular alterations in genes associated to cell proliferation, which can be induced by ultraviolet radiation. Among other genes, alterations on TP53 and DNA mismatch repair proteins (MMR) may be involved in the cellular proliferation observed in PTT. Based on this assumption, but also taking into account the close relationship between the sebaceous ducts and the external root sheath where TC develop, a MMR, a p53 expression assessment and a TP53 study were performed in a series of 5 PTT cases, including a giant one. We failed to demonstrate a MMR disorder on studied PTT, but we agree with previous results suggesting increased p53 expression in these tumours, particularly in proliferative areas. TP53 alteration was confirmed with FISH technique, demonstrating TP53 deletion in most cells.

Genomic landscape of a metastatic malignant proliferating tricholemmal tumor and its response to PI3K inhibition

Proliferating tricholemmal tumors (PTTs) are rare benign neoplasms that arise from the outer sheath of a hair follicle. Occasionally, these PTTs undergo malignant transformation to become malignant proliferating tricholemmal tumors (MPTTs). Little is known about the molecular alterations, malignant progression, and management of MPTTs. Here, we describe the case of a 58-year-old female that had a widely metastatic MPTT that harbored an activating PIK3CA mutation and was sensitive to the PI3K inhibitor, alpelisib (BYL719). We review the available literature on metastatic MPTT, detail the patient's course, and present a whole genome analysis of this rare tumor.

CD34 and BerEP4 Are Helpful to Distinguish Basaloid Tricholemmoma From Basal Cell Carcinoma

Tricholemmoma, a benign follicular neoplasm with outer root sheath differentiation, typically comprises clear or pale cells, and when multiple is pathognomic of Cowden's syndrome. The tumor is probably underrecognized and in basaloid examples can be difficult to distinguish from basal cell carcinoma (BCC). We studied 55 tricholemmomas (including 15 basaloid cases) and compared immunohistochemical profile with nodular BCC from our archives. Basaloid and non-basaloid tricholemmomas had similar staining characteristics. BerEP4 was focally positive (range 10%-20%) in only 3/39 (7.7%) tricholemmomas compared with widespread positivity in BCC (90.8%, 139 of 151 cases with ≥50% tumor area stained). CD34 was expressed, usually focally (median 20%, range 10%-90%), in 52/53 (98.1%) tricholemmomas and was negative in all 21 BCCs stained. EMA staining lacked sensitivity or specificity in differentiating tricholemmoma from BCC. Five or more Merkel cells were found in 7/17 (40.1%) tricholemmomas and 1/23 (4.3%) nodular BCCs studied. In summary, immunohistochemistry is helpful in distinction between tricholemmoma, including difficult basaloid examples (BerEP4 negative or focal, CD34 positive) compared with BCC (BerEP4 widespread in most cases, CD34 negative). The presence of 5 or more Merkel cells is a relatively specific but not a particularly sensitive discriminator.

Giant proliferating trichilemmal cyst arising from a nevus sebaceus growing for 30 years

Nevus sebaceus of Jadassohn, a congenital cutaneous hamartoma, has the potential to develop into various epidermal adnexal-origin neoplasms. While the most common neoplasms are trichoblastoma or syringocystadenoma, proliferating trichilemmal cysts are exceptionally rare. We report a case of a 63-year-old Cuban male with a giant proliferating trichilemmal cyst arising from a nevus sebaceus on the right shoulder which had been growing for 30 years. Proliferating trichilemmal cysts arising from nevus sebaceus cases are difficult to diagnose clinically and histologically as they are very rare and have not been defined by exact diagnostic criteria. Our case creates awareness of this particular tumor in nevus sebaceus and shares clinical and histological diagnostic information that can be used to make a proper diagnosis.

Metastatic trichilemmal carcinoma in a patient with breast cancer

Trichilemmal carcinoma (TC) is described as a very rare cancer of the skin adnexa.^{1 2} Ninety per cent of the lesions present on the scalp. Prognostic factors in TC are limited to lymph node status and surgical margins, with no statistical significance observed for age or gender of the patient, size of tumour or locoregional recurrence. We present a 46-year-old black patient who developed TC during treatment for breast cancer. Postoperative histology of the scalp lesion excision confirmed no involved margins. At the three monthly appointment, the patient was reviewed and multiple, new scalp lesions were noted. A CT scan of the head, neck found multiple lesions on the scalp, limited to the soft tissue, not involving the outer table of the skull. There was bilateral invasion of the parotid glands. To the best of our knowledge, no syndromes or associations between breast cancer and adnexal skin tumours exist.

A Rare Cutaneous Adnexal Tumor: Malignant Proliferating Trichilemmal Tumor

Proliferating trichilemmal tumors (PTTs) are neoplasms derived from the outer root sheath of the hair follicle. These tumors, which commonly affect the scalp of elderly women, rarely demonstrate malignant transformation. Although invasion of the tumors into neighboring tissues and being accompanied with anaplasia and necrosis are accepted as findings of malignancy, histological features may not always be sufficient to identify these tumors. The clinical behavior of the tumor may be incompatible with its histological characteristics. Squamous-cell carcinoma should certainly be considered in differential diagnosis because of its similarity in morphological appearance with PTT. Immunostaining for CD34, P53, and Ki-67 is a useful adjuvant diagnostic method that can be used in differential diagnosis aside from morphological findings. In this study, we aimed to present the case of a 52-year-old female patient with clinicopathological features. We reported a low-grade malignant proliferating trichilemmal tumor in this patient and detected no relapse or metastasis in a 24-month period of follow-up.

Cystic tricholemmal carcinoma in situ

An 89-year-old man presented with a clinically cystic 4-mm papule on the left temple. The clinical impression was a benign cyst. Pathologic examination revealed a small, symmetric-appearing, well-circumscribed, dermal-based cystic lesion with markedly atypical-appearing clear to squamoid cells lining the cyst wall, consistent with carcinoma in situ involving the cyst. The cells showed abundant glycogen-containing cytoplasm (confirmed by Periodic acid Schiff stains with and without diastase), consistent with tricholemmal differentiation, and areas of tricholemmal/pilar-type keratinization (without a granular layer), consistent with tricholemmal carcinoma in situ, most likely arising in a tricholemmal/pilar cyst. Ki-67 and p53 immunohistochemical stains were strongly positive (with more than 20% of nuclei staining on Ki-67 and more than 80% on p53) in the cyst-lining cells, further supporting the interpretation of carcinoma in situ. Multiple deeper level sections were examined but did not show any evidence of an associated invasive carcinoma. Tricholemmal (pilar) cysts are common benign adnexal lesions and atypia/dysplasia or carcinoma in situ arising within them is exceedingly rare. Previously, only one case of a tricholemmal cyst with carcinoma in situ has been reported. That case was associated with an atypical fibroxanthoma. We report only the second case of tricholemmal carcinoma in situ, most likely involving a tricholemmal cyst, which was not associated with another tumor or evidence of invasive carcinoma.

Recurrent proliferating trichilemmal tumor of the vulva: a case report

Proliferating trichilemmal tumor (PTT) is a rare but morphologically distinct tumor that usually arises on the scalp of elderly women. It is composed of multiple cysts consisting of squamous epithelium with trichilemmal keratinization without granular layer interposition. Vulvar proliferating trichilemmal cyst is very rare, with, to the best of our knowledge, only 3 cases previously reported in the literature. We describe a 39-year-old woman with recurrent PTT on the left labium majus of the vulva, which had been excised from the same side 5 years before. She had a palpable nodule, approximately 2 cm in size, which was firm, mobile, and nontender; without erythema and ulceration; and covered by normal skin on the vulva. There was no inguinal lymphadenopathy. The lesion was removed by wide surgical excision; because of the tissue elasticity, primary closure was possible. The pathology result was reported as proliferating trichilemmal carcinoma with tumor-free margins. Although local recurrence after wide excision is rare, we recommend complete excision for treatment of PTT and long-term follow-up because of the possibility of recurrence.

Malignant proliferating trichilemmal tumor involving the sinuses

Proliferating trichilemmal tumor (PTT) is a rare adnexal neoplasm that arises from the outer sheath of the hair follicle. It is believed that PTTs originate in trichilemmal cysts. These tumors have the potential for malignant transformation; when this occurs, the tumor is known as a malignant PTT (MPTT). Recurrence after simple local excision is common, and it can cause considerable morbidity. We report a case of MPTT that was initially diagnosed as a benign PTT. The primary tumor had arisen from the skin over the glabella. It was excised, but it recurred 3 years postoperatively. The recurrent tumor involved the eyelid, nasal cavity, and frontal and ethmoid sinuses, and it extended into the orbit. The recurrent tumor was excised via combined endoscopic and open surgery. As far as we know, this is the first documented case of an MPTT that involved the sinuses.

Malignant proliferating trichilemmal tumour presenting early in life: an uncommon feature

Malignant proliferating trichilemmal tumour is a rare cutaneous malignant neoplasm usually occurring in elderly women. We present a case of malignant trichilemmal tumour in a young lady of 26 years of age with a previous history of proliferating trichilemmal tumour at the same site.

Trichilemmal carcinoma of the upper eyelid: a case report

We report a very rare case of trichilemmal carcinoma (TLC) involving the upper eyelid. To the best of our knowledge, this is the first report of trichilemmal carcinoma of the upper eyelid in Korea. A 51-year-old man presented to our hospital complaining of a bloody discharge from his left upper eyelid. He had a soft and lobulated mass on the palpebral conjunctiva. An incisional biopsy revealed trabecular growth of tumor cells with clear cytoplasm, prominent nucleoli, frequent mitoses, and foci of trichilemmal keratinization. Immunohistochemically, the lesion was positive for p53 and negative for CD 34. A diagnosis of TLC was made, and total excision of the mass and reconstruction of the eyelid were performed. Trichilemmal carcinoma is a rare malignant tumor, though it appears to be an indolent neoplasm with no metastatic potential. The treatment of choice for trichilemmal carcinoma of the eyelid is complete excision with tumor-free margins due to the locally invasive nature of the lesion.

Fine-needle aspiration cytology in the diagnosis of malignant proliferating trichilemmal tumor: Report of a case and review of the literature

Malignant proliferating trichilemmal tumor is a rare cutaneous neoplasm derived from the outer root sheath of the hair follicle. Fine-needle aspiration cytology is being increasingly used in the investigation of primary and metastatic cutaneous tumors. However, there are few reports on the cytology of trichilemmal tumors in the literature. We describe the cytological features of this uncommon adnexal tumor presenting as a scalp mass in a 58-year-old woman. In view of its aggressive biological behavior, it is crucial for cytologists to be aware of this rare lesion and distinguish it from primary cutaneous squamous-cell carcinoma. The differences on fine-needle aspiration cytology can be subtle and pose problems in diagnosis.

CD34-reactive tumors of the skin. An updated review of an ever-growing list of lesions

Over the past few years, a growing number of cutaneous tumors expressing CD34 is being reported. The list contains benign and malignant neoplasms as well as reactive and hamartomatous lesions of diverse lineages of differentiation, including fibroblastic, myofibroblastic, fibrohistiocytic, vascular, neural, adipocytic, smooth muscle, hematopoietic, melanocytic and epithelial. The more frequent diagnostic difficulties are found in spindle cell proliferations, mainly in those of the fibrocytic lineage. In part, this is because of the fact that in this area are, aside to well-defined entities, histologically and clinically diverse, recently reported cutaneous CD34-reactive lesions, whose definitions, limits and relationships are not completely established. The CD34 expression plays a key role in the differential diagnosis of some tumors, such as dermatofibrosarcoma protuberans, epithelioid sarcoma or pleomorphic hyalinizing angiectatic tumor of soft parts, with important therapeutic consequences. In others, as in desmoplastic trichilemmoma, it can help to resolve diagnostic problems in concrete cases. Finally, in many of the CD34-positive lesions, the diagnosis with the hematoxylin and eosin stain is straightforward. However, in all of them, the knowledge of the immunohistochemical profile contributes to our understanding of the cutaneous pathology.

Proliferating trichilemmal tumors: a review of the literature

BACKGROUND

Proliferating trichilemmal tumors (PTTs) are uncommon lesions whose histologic hallmark is the presence of trichilemmal keratinization. PTT is thought to originate from the trichilemmal cyst (TC) and have the potential for malignant transformation, at which point it is termed a malignant proliferating trichilemmal tumor (MPTT). These lesions may cause considerable morbidity and even mortality, and recurrence after simple local excision is common.

OBJECTIVE

The objective was to review the clinical presentation, histopathologic characteristics, malignant potential, and treatment options for PTT.

METHODS

The English literature was reviewed regarding PTT, TC, and MPTT.

RESULTS

PTT generally presents as a subepidermal tumor on the scalp in women over the age of 60. Histologic findings may be used to differentiate PTT from TC and MPTT. Complete surgical excision is recommended; additional radiotherapy and/or chemotherapy may be used for lesions with increased invasive potential.

CONCLUSION

Adequate treatment of PTT requires skilled histopathologic examination for proper diagnosis; histologic appearance may not correlate with clinical behavior. After surgical excision, long-term clinical follow-up for evidence of metastatic disease is judicious.

Mohs' Micrographic Surgery of a Proliferating Trichilemmal Tumor in a Young Black Man

BACKGROUND

Proliferating trichilemmal tumor is an uncommon tumor of the follicular isthmus of the hair follicle. It usually presents as a solitary nodule on the scalp of older white women. Although these lesions typically behave in a benign fashion, recurrences and metastasis after local excision have been reported. Mohs' micrographic surgery has been effectively used to treat adnexal neoplasms.

OBJECTIVE

To report a case of a proliferating trichilemmal tumor in a young black man, which was excised using Mohs' micrographic surgery.

METHODS

Case report and review of the literature.

RESULTS

Mohs' micrographic surgery demonstrated an irregular extension of the tumor beyond a 1 cm surgical margin.

CONCLUSIONS

Proliferating trichilemmal tumors should be considered in the differential diagnosis of cutaneous neoplasms on the scalp in persons of any age (with the possible exception of infants and children), sex, or race. Mohs' micrographic surgery may be considered an optimal treatment option for proliferating trichilemmal tumors because these lesions may have an infiltrative component that may not be clinically apparent.

Metastatic malignant proliferating trichilemmal tumor detected by positron emission tomography

BACKGROUND

Whole-body 18F-fluorodeoxyglucose-positron emission tomography (18F-FDG-PET) was introduced in 1990s, and its efficacy for cerebral mapping and for selective detection of various malignancies is now being recognized.

OBJECTIVE

To report on the usefulness of whole-body 18F-FDG-PET for detecting a metastatic lesion in a rare case of malignant proliferating trichilemmal tumor.

METHODS

A malignant proliferating trichilemmal tumor on the occipital scalp of a 69-year-old female recurred on the margin of the surgical scar after an initial wide excision, and it was removed by Mohs micrographic surgery. 18F-FDG-PET was done to detect any remaining tumor tissue, and it showed a hot uptake on the lower left occipital area, where a pea-sized nodule formed 2 months later. Dissection and wide excision of the nodule showed metastatic malignant proliferating trichilemmal tumor cells in the lymph nodes.

RESULTS

We were able to take advantage of the high resolution of the 18F-FDG-PET in detecting a metastatic lesion despite its proximity to the central nervous system.

CONCLUSION

The 18F-FDG-PET can be used in future malignant proliferating trichilemmal tumor cases to study the metastatic characteristics of this rare tumor.

Proliferating trichilemmal tumor with a malignant spindle cell component

BACKGROUND

Proliferating trichilemmal tumors (PTTs) are uncommon exuberant growths of cells derived from the external root sheath. They tend to occur in older women, with a predilection for the scalp. Resection is usually curative. Spindle cell components arising within PTTs are exceedingly rare, with only three known cases previously reported. Of these three cases, one patient died from widespread metastasis.

METHODS

Histological and immunohistochemical examinations were performed on a tumor from a 54-year-old man which, after exhibiting slow growth for 3 years, increased rapidly in size.

RESULTS

Microscopic examination revealed cystic lobules of squamous cells without a granular cell layer surrounding amorphous eosinophilic debris within the dermis. Also present was a poorly circumscribed focus of spindle cells with hyperchromasia, pleomorphism, giant cells, and abundant mitoses, including abnormal forms. Immunohistochemistry showed the spindle cells to stain positively for vimentin, but negatively for keratin, epithelial membrane antigen and S-100 antibodies.

CONCLUSION

A malignant spindle cell component arising within a PTT is a rare neoplasm which has been associated with death from widespread metastasis.

Proliferating trichilemmal cyst: report of two cases, one benign and the other malignant

Proliferating trichilemmal cyst (PTC) is a rare but morphologically distinct tumor that usually arises on the scalp of elderly women. We report two cases of PTC, one benign and the other malignant. PTCs are well circumscribed, subepidermal lesions and demonstrate a uniform histologic pattern with varying degrees of cytological atypia. Malignant proliferating trichilemmal cyst (MPTC) has features in common with benign proliferating trichilemmal cyst (BPTC), including a central area of abrupt keratinization and hyperplastic squamous epithelium forming solid areas. The diagnosis of MPTC is essentially based on histological features. The presence of a high mitotic rate, atypical mitosis, severe nuclear pleomorphism, and tumor invasion of the adjacent tissues are the essential histological features of malignancy in these unusual tumors. The therapeutic approach in malignant cases is the same as that in the treatment of BPTC: surgical removal with a wide clear margin. However, even with adequate resection, both tumors tend to recur locally.

Differentiation between malignant and benign follicular adnexal tumours of the skin by DNA image cytometry

BACKGROUND

We have demonstrated in previous studies that DNA image cytometry (DNA ICM) can be helpful in detecting malignancy in sebaceous tumours of the Muir-Torre syndrome and sweat gland tumours. However, little is known about DNA ICM in cutaneous adnexal tumours with follicular differentiation.

OBJECTIVES

To study a larger series of benign and malignant follicular adnexal tumours with DNA ICM.

METHODS

We studied 13 malignant follicular tumours (seven trichilemmal carcinomas, five malignant proliferating pilar tumours, one pilomatrix carcinoma) and 55 benign follicular tumours (four tumours of the follicular infundibulum, seven Winer's pores, eight trichilemmomas, two trichofolliculomas, 16 trichoepitheliomas, 13 pilomatrixomas, five trichoblastomas) by DNA ICM. All cases were clear-cut as malignant or benign, respectively, on histopathological criteria. The stemline interpretation according to Böcking et al. (DNA distribution in gastric cancer and dysplasia. In: Precancerous Conditions and Lesions of the Stomach, Zhang YC, Kawai K, eds. Berlin: Springer-Verlag, 1993: 103-20) was performed in all cases. In addition, 5[c]-exceeding events (5cEE) and the 2[c] deviation index (2cDI) were calculated, except in one histopathologically benign tumour, which revealed euploid polyploidization, as the analysis of 5cEE and 2cDI is not valid in that case.

RESULTS

A 2cDI threshold of 0.24 proved to be the most reliable marker for the distinction between malignant and benign follicular tumours. On the basis of this feature, all malignant and benign tumours were correctly classified. A specificity of 100% was achieved by all three interpretation methods, but the sensitivity of 2cDI for the detection of malignant tumours was superior to the analysis of 5cEE (sensitivity 77%) and to the stemline interpretation (sensitivity 23%).

CONCLUSIONS

DNA ICM may be helpful in distinguishing between malignant and benign follicular tumours.

Malignant proliferating trichilemmal tumor

Proliferating trichilemmal tumors are uncommon neoplasms that are usually benign, but characterized by frequent local recurrence. In this report, we describe a patient who sought treatment at our clinic for a right occiput scalp nodule measuring 1 cm in diameter. The subcutaneous lesion was mobile and without overlying skin ulceration. Excisional biopsy of the mass was performed and the pathologic diagnosis returned as malignant, proliferating trichilemmal (pilar) tumor. Resection margins were free of tumor. On further examination the patient had no evidence of metastatic disease. A schedule of routine follow-up visits was arranged to monitor the site for recurrent disease.

Proliferating trichilemmal cyst with focal invasion: report of a case and a review of the literature

Proliferating trichilemmal cyst (PTC) is a rare but morphologically distinctive tumor that usually occurs in the scalp of elderly women. Furthermore, only 30 well-documented examples of so-called malignant PTC have been reported. Alternatively, some authors have recently proposed that PTC is squamous cell carcinoma. We describe a case of PTC with focal invasion that was indistinguishable from squamous cell carcinoma in areas, and we review the literature. This debate should be considered in PTCs to provide adequate treatment (wide local excision) and follow-up (long term), particularly in large and long-standing lesions.