Squamous cell carcinoma with clear cells: how often is there evidence of tricholemmal differentiation?

Follicular (Infundibular-Tricholemmal) Squamous Cell Carcinoma: A New WHO Entity. Clinicopathological Features in 103 Cases, Including Follow-Up and Implications for Patient Management

AIMS

Cutaneous follicular (infundibular-tricholemmal) squamous cell carcinoma (FSCC) is a new World Health Organization entity. We present the largest series of published cases, summarizing clinical data, diagnostic criteria, differential diagnosis, and implications for patient management.

METHODS

Cases were identified from 2004 to 2011. Inclusion criteria included discrete attachment(s) of the tumor to the overlying epidermis via follicular infundibula, tricholemmal keratinization, and cellular pleomorphism. Keratoacanthoma and lesions with adjacent bowenoid epidermal dysplasia were excluded.

RESULTS

One hundred three cases of FSCC identified. 48.5% demonstrated completely circumscript borders ( in situ for practical purposes), 12.6% uncertain for invasion (overwhelmingly pushing borders), and only 38.8% as clearly invasive. Follicular mucin in acantholytic spaces within tumor epithelium was a distinctive finding in 57.2% of cases. Clinical data indicated predominance in elderly (median 78.5 years) men (70.4%), with preferential head and neck location (81.6%). Many were clinically suspected as squamous cell carcinoma (48.5%). However, a significant minority were clinically diagnosed as basal cell carcinoma (40.8%). This may reflect that FSCC commonly presented as a papule or nodule (51.3%). By contrast, keratoacanthoma was less frequently suggested (17.2%) and still fewer lesions were suspected to be actinic keratosis/Bowen's disease (13.6%). Follow-up in 82 cases (median 26.5 months, range 3-144) identified 5 (6.1%) local recurrences. There was no instance of metastasis in the subgroup of lesions with completely circumscript borders. Three of 45 (6.7%) patients, with follow-up, considered to have tumors with invasive pushing, and/or infiltrative borders developed lymph node metastases.

CONCLUSIONS

FSCC is identified as a common skin cancer, incorporating historical entities, such as infundibular carcinoma and tricholemmal carcinoma, with readily identifiable histologic features. Correct diagnosis has implications for patient management; a significant subgroup of lesions show completely circumscript borders that are considered in situ for practical purposes.

Extra-Ocular Sebaceous Carcinoma in Situ of the Arm of an Elder Male: An Unusual Presentation in an Atypical Location

Background. Sebaceous carcinoma in situ outside the ocular region is an exceedingly uncommon. It is an intraepidermal neoplasm originating from sebaceous glands limited to the epidermis with no invasion into the underlying dermis or beyond. Although sebaceous carcinoma in situ is predominantly observed in ocular regions, particularly the eyelids, instances of its occurrence in extraocular locations are infrequent, with only a limited number of examples reported in the literature. Case Presentation. A 63-year-old man presented with a left posterior arm lesion. Microscopic examination revealed a proliferation of poorly differentiated atypical neoplastic sebocytes confined to the epidermis with pleomorphic nuclei, prominent nucleoli, and clear cell changes. The neoplastic cells demonstrated positive staining for adipophilin, androgen receptor, epithelial membrane antigen, P63, BerEP4, and keratin 7. Microsatellite instability markers showed preserved nuclear staining for MLH1, PMS2, MSH2, and MSH6. A definitive diagnosis of sebaceous carcinoma in situ was rendered. Discussion. The distinctive histopathologic characteristics typically involve the presence of atypical sebaceous cells confined within the epidermis. Atypical cells often exhibit enlarged nuclei, increased mitotic activity, and prominent nucleoli. A panel of epithelial membrane antigen, adipophilin, and androgen receptors is essential for ensuring an accurate diagnosis. Conclusion. This report underscores the importance of considering sebaceous carcinoma in situ in diagnosis in atypical locations, emphasizing the need for a comprehensive histopathologic examination and immunohistochemical staining panel. This article aims to demonstrate the rarity of sebaceous carcinoma in situ in extraocular sites to broaden our understanding of its diverse clinical presentations.

Systematic analysis and case series of the diagnosis and management of trichilemmal carcinoma

Background

Trichilemmal carcinoma (TLC) is a rare malignant cutaneous adnexal neoplasm, with no relatively comprehensive research.

Objective

The aim of this study is to perform an updated statistical analysis so as to better understand TLC's epidemiology, clinical features, diagnosis, and treatment.

Methods

The diagnosis and treatment of three TLC cases in our department were summarized. Then, all TLC cases published in the literature were retrieved for a comprehensive analysis, followed by the analysis of global trends and regional distribution, demographic characteristics, clinical features, pathogenesis, histopathological features, and treatment and prognosis of TLC.

Results

Of the 231 cases, the incidence of TLC has shown an upward trend recently, especially in China, in Asia. The susceptible population is men aged 60-80 and women over 80, and the most prone location is head and neck. The phenotype of TLC is not always typical and may be misdiagnosed because of the coexistence of other diseases. There is a linear relationship between the diameter and its duration or thickness. UV, locally present skin lesions, trauma, scarring, organ transplantation, and genetic disorders may trigger the occurrence of TLC. Periodic acid-Schiff staining and CD34, but not Epithelial Membrane Antigen (EMA), were helpful in the diagnosis of TLC. Although effective, surgical excision and Mohs micrographic surgery need further improvement to reduce recurrence of TLC. Carcinoma history is an independent risk factor for TLC recurrence.

Limitations

The limitation of this study is the lack of randomized controlled trial on TLC treatment and recurrence.

Conclusion

TLC has the possibility of invasive growth and recurrence, especially in patients with longer duration and carcinoma history.

Huge Trichilemmal Carcinoma With Metastasis Presenting With Two Distinct Histological Morphologies: A Case Report

Background

Trichilemmal carcinoma (TC) is a rare malignancy of cutaneous adnexal carcinoma, with only 136 cases reported in the literature to date. It usually has an indolent course and benign clinical evolution, and only four cases with regional and distant metastasis have been reported. Tumor cells present with the characteristics of trichilemmal differentiation on both histological and immunohistological examination.

Case Presentation

We report a case of TC on the scalp with an aggressive course and metastasis to the ipsilateral neck. Moreover, the lesions presented with two distinct histological morphologies.

Conclusion

Despite an indolent course and benign clinical evolution, TC has the potential for local invasion and recurrence, which implies that accurate early diagnosis and careful follow-up are very important for these patients. More than one specimen should be obtained for histopathological examinations when the lesion is very large and characterized by different morphologies.

Clear Cell Proliferations of the Skin: A Histopathologic Review

ABSTRACT

Cutaneous clear cell proliferations encompass a heterogenous group of several primary cutaneous neoplasms and metastatic tumors with different histogenesis. Many of these clear cell proliferations may seem strikingly similar under the microscope resulting in challenging diagnosis. In many of these clear cell lesions, the reason for the clear or pale appearance of proliferating cells is unknown, whereas in other ones, this clear cell appearance is due to intracytoplasmic accumulation of glycogen, mucin, or lipid. Artifacts of tissue processing and degenerative phenomenon may also be responsible for the clear cell appearance of proliferating cells. Awareness of the histopathologic findings as well as histochemical and immunohistochemical techniques are crucial to the accurate diagnosis. This review details the histopathologic features of clear cell cutaneous proliferations, classifying them according their type of differentiation and paying special attention to the histopathologic differential diagnosis among them.

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.

Cutaneous tricholemmal carcinoma: a 15-year single center experience

BACKGROUND

Clear cell morphology has been described in several cutaneous neoplasms either as a specific feature of some entities either as a morphological variant in the spectrum, and these two entities are frequently considered together in the differential diagnosis.

METHODS

We reviewed our series of cases occurred in our laboratory in order to further quantify the number of cases showing morphological features of tricholemmal differentiation and to investigate other clinical or histological difference. We retrieved 91 cases and, for each of them, all the clinical data regarding age, sex, clinical features, and clinical suspicious were collected, when available.

RESULTS

The revision of the specimens concluded with a final diagnosis of tricholemmal carcinoma in 15 cases (17%), all the other cases were thus considered as squamous cell carcinoma with clear cell features. No statistically significant correlations were observed with the demografic or clinicopatholagical parameters such as age, sex or dimensions, but morphological revision highlighted a potentially greater "vertical" growth frequently not matched by a concomitant radial one in tricholemmal carcinoma than in squamous tumors.

CONCLUSIONS

The debate upon the diagnostic distinction of these tumors is still ongoing with authors proposing the tricholemmal carcinoma as a variant of a squamous cell carcinoma rather than a distinct entity. Further studies are needed to confirm our data and to evaluate the reproducibility of this feature.

A previously undescribed variant of cutaneous clear-cell squamous cell carcinoma with psammomatous calcification and intratumoral giant cell granulomas

Cutaneous clear-cell squamous cell carcinoma (ccSCC) is a rare variant of SCC composed of clear cells that lack cytoplasmic glycogen or evidence of tricholemmal keratinization. We report a previously undescribed variant of ccSCC with psammomatous calcification and intratumoral giant cell granulomas. The differential diagnosis with trichilemmal carcinoma is outlined according to the criteria of the fourth edition of World Health Organization (WHO) classification. Our findings outline that psammomatous calcification may occur inside the keratinous pearls of the neoplastic lobules triggering an intratumoral giant cell granulomatous reaction. The prognostic significance of this histopathological presentation is unknown but the potential for formation of psammoma bodies in cSCC should be considered to avoid diagnostic pitfalls.

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.

Could EMA and cytokeratin 7 be useful in distinguishing tricholemmal carcinoma from clear-cell squamous cell carcinoma? A case series from our department and a brief review of the literature

Tricholemmal carcinoma is a malignant cutaneous adnexal tumor showing outer root sheath differentiation, thought to be the malignant counterpart of trichilemmoma. Although the real existence of tricholemmal carcinoma continues to be a matter of debate, it has been introduced in the recently published 4th edition of World Health Organization classification of skin tumors. Herein, we evaluated whether immunohistochemistry (EMA, CK7, CK5/14, p63, p16, and Ber-EP4) supports tricholemmal carcinoma as a separate entity and whether it could be useful in this differential diagnosis. A total of 9 cases, 3 tricholemmal carcinomas and 6 clear-cell squamous cell carcinomas were evaluated on the basis of histological criteria suggested by the WHO. In our opinion, although these results need to be validated in larger series, they support tricholemmal carcinoma as a separate entity and suggest an immunohistochemical profile (clear-cell squamous cell carcinomas: EMA diffusely positive, CK7 negative; tricholemmal carcinoma: EMA negative, CK7 patchy or moderately positive) that could be useful for this differential diagnosis.

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.

Seborrheic Keratosis With Prominent Clear Cell Changes-A Rare But Important Diagnostic Variant

Seborrheic keratoses, although exceedingly common, occasionally have morphologic similarities to other lesions that complicate a typically straightforward diagnosis. The authors present a case of a 69-year-old man with a left shoulder lesion that displayed characteristic clinical and microscopic features of seborrheic keratosis on biopsy. However, diffuse and prominent clear cells were also noted. These stained strongly with Periodic acid-Schiff and were diastase sensitive, suggestive of glycogen accumulation and possible trichilemmal differentiation. This case is presented to demonstrate a unique and striking example of clear cell change within a seborrheic keratosis and to briefly review the published literature on this finding, which is rarely reported and demands close examination to exclude more aggressive neoplasms.

Histopathologic pitfalls of Mohs micrographic surgery and a review of tumor histology

Mohs micrographic surgery is a specialized subset of staged surgical excisions with each subsequent stage being driven largely by the histologic findings of the previous stage. Therefore, it is imperative that histologic analysis is performed in an accurate manner. Frozen section and tissue flattening is a crucial step in Mohs surgery. Frozen sections introduce certain artifacts and these artifacts must be interpreted in the correct context. Basal and squamous cell carcinomas are the most common tumors encountered in Mohs micrographic surgery, and their histopathology is also associated with certain "pitfalls". Basal cell carcinoma should be distinguished from hair follicles, folliculocentric basaloid proliferations, poromas, nevus sebaceous, desmoplastic trichoepitheliomas, and spiradenomas, to name but a few histologic entities. Similarly, squamous cell carcinoma should be distinguished from hypertrophic actinic keratoses, pseudoepitheliomatous hyperplasia, sebaceous carcinoma, and microcystic adnexal carcinoma. In addition, there are numerous subtypes of basal cell and squamous carcinomas that the Mohs surgeon should be aware of due to differences in the biologic behavior of these tumors. This review presents a number of the common histologic pitfalls of Mohs micrographic surgery and a review of tumor histology.

Malignant Clear Cell Acanthoma: Report of a Rare Case of Clear Cell Acanthoma-Like Tumor With Malignant Features

An erythematous and moist tumor nodule on the left temple of a 92-year-old woman was biopsied and identified as a clear cell acanthoma (CCA)-like tumor with malignant cytology and high proliferation activity. This case is similar to 2 cases reported previously as atypical CCA. The authors believe that these tumors are malignant counterparts of CCA and propose to call them malignant CCA. The clinicopathologic features of the present case are described along with dermoscopic findings.

[Skin adnexal tumors with follicular differentiation]

Skin adnexal tumors with predominantly follicular differentiation represent a clinicopathological heterogeneous group of neoplasms and are classified according to the cytologically achieved differentiation of the follicular compartment. Given the complex structure of non-neoplastic hair follicles it is not surprising to find varying differentiations in neoplasms and there are overlapping clinicopathological features between the established entities. The use of immunohistochemical staining has only a limited value in the diagnosis of follicular neoplasms.

Androgen receptor identification in the diagnosis of eyelid sebaceous carcinomas

PURPOSE

To assess the role of androgen receptor detection in diagnosing eyelid sebaceous carcinomas and to compare it with that of adipophilin.

DESIGN

Retrospective, clinicopathologic study.

METHODS

Ten sebaceous carcinomas (8 invasive, 2 intraepithelial only) were stained immunohistochemically for androgen receptors and were compared with adipophilin staining. Receptor staining also was performed on benign sebaceous tumors (a sebaceoma and an adenoma) and as controls on eyelid basal cell carcinomas, eyelid squamous cell carcinomas, conjunctival squamous dysplasias, and conjunctival melanomas.

RESULTS

All 8 patients with an invasive component of sebaceous carcinoma underwent a biopsy in which the tumor cells showed diffusely positive results for androgen receptors (>20% of cells and usually >40%) and positive results for adipophilin. Eight cases displaying an intraepithelial (or pagetoid) component of spread also showed diffusely positive results for androgen receptors and adipophilin in at least 1 of multiple biopsy samples from each patient. However, in 8 of 21 separate conjunctival biopsy specimens with intraepithelial cytologic atypia, adipophilin results were negative. A sebaceoma and a sebaceous adenoma also showed positive results for both of these biomarkers. Among the controls, squamous carcinomas and melanomas showed negative results for androgen receptors and adipophilin. Basal cell carcinomas displayed focal receptor positivity in fewer than 5% of cells and showed negative results for adipophilin.

CONCLUSIONS

Androgen receptors and adipophilin can separate sebaceous tumors immunohistochemically from squamous carcinomas and melanomas, which showed negative results for both, and from basal cell carcinomas, which showed positive receptor results in a distant minority of cells. Regarding intraepithelial (or pagetoid) spread, androgen receptor detection was more sensitive and reliable than adipophilin in highlighting this component of the disease.

Trichilemmal carcinoma: an unusual presentation of a rare cutaneous lesion

Trichilemmal carcinoma (TC) is a rare cutaneous neoplasm which is derived from adnexal keratinocytes, is histologically invasive, contains cytologically atypical clear cell neoplasm and is in continuity with the epidermis and/or follicular epithelium. However, the diagnostic criteria and even the existence of TC have been contentious. We report the case of a 92-year-old woman with TC of the head and neck region who presented with an unusually long history. She was treated successfully with wide local excision. Important aspects in presentation, differential diagnosis, including histopathological features and management are discussed.

Clear cell variant of squamous cell carcinoma originating in the esophagus: report of a case with immunohistochemical and oncogenetic analyses

The cutaneous clear cell squamous cell carcinoma (SCC) is a rare tumor thought to be associated with hair follicle or skin appendage differentiation. We report herein a rare variant case of a clear cell SCC originating in the esophagus. A 70-year-old Japanese man was found to have a tumor in the esophagus. The excised neoplasm showed dominance of clear cell over conventional SCC components; the two components in an apparent continuum. The clear cells, regular in size with a moderate nuclear/cytoplasmic ratio and relatively hyperchromatic and centrally located nuclei, were compactly arranged in sheets. Glycogen deposition was apparent on PAS staining with or without diastase digestion and under the electron microscope. The clear cell SCC components were positive for cytokeratin (CK)7, CK8, CK18 and CK19, but were negative for CK5/6 or CK14. Reciprocal staining patterns of CKs were apparent in conventional SCC components. The present case and cutaneous clear cell SCC counterparts share some histopathologic characteristics whereas CKs expression differs between the two. Overexpression of p53 protein, without evidence of any mutation, and reduced p16(INK4a) were noted in both clear cell and conventional SCC components. No mutations of Kras, BRAF or β-catenin genes were found in both tumor components.

Primary squamous cell carcinoma of fallopian tube accompanied by gastric metaplasia of female genital tract: case report and review

Primary squamous cell carcinoma arising from the fallopian tube (SCCFT) is extremely rare with only six reported cases. We report a case of primary SCCFT accompanied by multifocal pyloric glandular metaplasia in the genital tract. An accompanying review of the literature describes the characteristics of this rare histological subtype invading into the muscular layer of the fallopian tube to involve adjacent pelvic organs, while the most common serous type tends to spread into the abdominal cavity through tubal ducts. Due to the low response rate of adjuvant therapies, the 5-year survival rate of patients bearing primary SCCFT at stage II-IV is very poor, only accounting for 25%. All patients were alive without disease where optimal resection had been successfully achieved. These findings imply that radical tumor resection is mandatory for satisfactory treatment of primary SCCFT.