Aberrant p16, p53 and Ki-67 immunohistochemistry staining patterns can distinguish solitary keratoacanthoma from cutaneous squamous cell carcinoma

Keratoacanthoma (KA) is widely considered a benign, usually self-resolving, neoplasm distinct from cutaneous squamous cell carcinoma (cSCC), while some consider KA to be indistinguishable from cSCC. Published studies indicate utility for p16, p53, Ki-67 immunostaining and elastic van Gieson (EVG) in the assessment of KA and cSCC. We compared clinical features and staining patterns for p16, p53, Ki-67 and EVG in fully excised KA, cSCC with KA-like features (cSCC-KAL) and other cSCC (cSCC-OTHER). Significant differences between KA, cSCC-KAL and cSCC-OTHER were found for head and neck location (20%, 86%, 84%), and duration <5 months (95%, 63%, 36%). KA shows both a mosaic pattern for p16 (>25-90% of neoplasm area) and peripheral graded pattern for p53 (up to 50% moderate and strong nuclear staining) in 92% compared with 0% of cSCC-KAL and 0% of cSCC-OTHER. In contrast, a highly aberrant pattern (usually null) for one or both p16 and p53, was present in 0% of KA, 83.8% of cSCC-KAL and 90.9% of cSCC-OTHER. Abnormal distribution of Ki-67 beyond the peripheral 1-3 cells was uncommon in KA (4.2%) and common in cSCC-KAL (67.6%) and cSCC-OTHER (88.4%). Moderate to striking entrapment of elastic and collagen fibres was present in the majority of KA (84%), cSCC-KAL (81%) and cSCC-OTHER (65%). KA are clinically distinct neoplasms typically of short duration occurring preferentially outside the head and neck and generally lacking aberrations of p16, p53 and Ki-67, compared with cSCC that have high rates of aberrant or highly aberrant p16, p53 and Ki-67, but EVG lacked specificity.

The occurrence of non-melanoma malignant skin lesions and non-cutaneous squamous-cell carcinoma among metastatic melanoma patients: an observational cohort study in Denmark

BACKGROUND

Inhibitors of mutant BRAF are emerging as standard of care in patients with metastatic melanoma who carry relevant oncogenic mutations. However, BRAF inhibitors are found to induce cutaneous squamous cell carcinoma (cuSCC). Population-based background rates of cuSCC and non-cutaneous squamous cell carcinoma (non-cuSCC) in the metastatic melanoma population may contextualize safety signals from randomized clinical trials or the clinics. However, these background rates are lacking.

METHODS

We conducted a historical cohort study to evaluate the background rates of new-onset non-melanoma skin lesions and non-cuSCC among 2,814 metastatic malignant melanoma patients diagnosed in 1997-2010, identified through the Danish Cancer Registry and the National Pathology Registry. Patients were excluded if they had a history of cancer before the metastatic melanoma diagnosis, other than skin cancers. We determined the incidence of non-melanoma malignant skin lesions and non-cuSCC that occurred post metastatic melanoma diagnosis, censoring patients at death, emigration, or December 31, 2011 (end of study period), whichever came first.

RESULTS

The median age at metastatic melanoma diagnosis was 64 years. Over 40% of patients died within one year of metastatic diagnosis and ~70% died within 5 years. The percentages of patients with prior history or prevalent disease at metastatic melanoma diagnosis included: 8.6% with cuSCC or basal cell carcinoma (BCC), 3.9% with actinic keratosis (AK), and 0.7% with Bowen's disease. No patients had past or current non-cuSCC per study exclusion criterion. The incidence of non-melanoma skin lesions during the 6 months post-metastatic melanoma diagnosis was as follows: BCC, 1.8% (42.5 per 1000 person-years [PY]); AK, 0.8% (18.6 per 1000 PY); cuSCC, 0.1% (1.7 per 1000 PY); Bowen's disease, 0.04% (0.8 per 1000 PY); and keratoacanthoma (KA), 0%. Non-cuSCC was observed in 3 patients (0.1%; 2.5 per 1000 PY) at 3 sites: bronchi, heart and lung.

CONCLUSION

CuSCC and non-cuSCC were rare events among metastatic melanoma patients.

Images in transplant dermatology

Transplant recipients can develop various skin conditions throughout their lives. Of concern are skin cancers, which are best treated with early detection. We report two cases seen in the transplant dermatology clinic in Singapore General Hospital.

Keratoacanthoma of the Lip: Activation of the mTOR Pathway, Tumor Suppressor Proteins, and Tumor Senescence

The PI3K-PTEN-mTOR is one of the most important pathways involved in cancer development and progression; however, its role in keratoacanthoma (KA) is poorly understood. In this study, we investigated the activation of key proteins in the PI3K-mTOR pathway in lip KA. We analyzed the activation of the PI3K-PTEN-mTOR pathway using human tumor samples stained for well-established protein markers in this pathway, including pS6 and pAKT phosphoproteins. We assessed proliferation using Ki-67 and performed additional morphological and immunohistochemical analysis using anti-PTEN and anti-p16 antibodies.We found that the majority of KA labeled to pS6 and not pAKT. PTEN expression was inversely correlated with Ki-67 expression. In addition to PTEN expression, KA cells were positive for p16 senescence marker. PI3K-PTEN-mTOR pathway is activated in lip KA, leading to downstream activation of mTORC1, but not mTORC2. This pathway plays an important role in KA progression by promoting proliferation and activation of oncogenic-induced senescence.

Keratoacanthoma and Keratoacanthoma-Like Squamous Cell Carcinoma: Similar Morphology but Different Pathogenesis

Differential diagnosis between keratoacanthoma (KA) and squamous cell carcinoma (SCC) is difficult due to their similarities. The mechanisms that drive their distinct biological behavior are poorly understood. To investigate whether the assessment of microvessel density (MVD) could be helpful in KA and SCC differential diagnosis and to gain insight into the pathogenesis of KA-like neoplasms, we compared the density of CD105- and CD34-stained vessels in KAs and SCCs and their relation to the expression of the p53 oncoprotein and proliferation marker Ki67. This is an observational retrospective cohort study. Forty lesions with clinical appearance of KAs (29 KAs and 11 SCCs) entered the study. A biopsy was taken from each lesion at presentation and the natural clinical course was monitored for at least 1 month. Growing or minimally regressing lesions were submitted to complete surgical excision. The diagnoses were established on combined clinical, histological, and follow-up evaluations. The MVD and p53 or Ki67 expression in neoplastic cells were assessed through morphometry. The MVD did not show discriminating power between KAs and SCCs. The Ki67 proliferation rate was significantly higher in SCCs. Although neoangiogenesis (CD105-MVD) in KAs was associated with cell proliferation, in SCCs it was not. There was significant correlation between p53 expression and neoplasia size in SCCs but not in KAs. From our results, we may conclude that KA and SCC have similarities, as CD105- and CD34-MVD. However, the low Ki67 proliferation index and the positive correlation between Ki-67 index and neovascularization in KA suggest a dependence in neovascularization to grow in KA, pointing to involvement of distinct pathogenesis.

Recurrent facial keratoacanthoma in a patient with diabetes: a case report

Background

Keratoacanthoma is a relatively common low-grade malignancy that originates in the pilosebaceous glands. Pathologically, it closely resembles squamous cell carcinoma. Keratoacanthoma is believed to have a good prognosis; however, it has been reclassified as squamous cell carcinoma, keratoacanthoma type, to reflect the difficulty in histologic differentiation of this lesion as well as its uncommon but potentially aggressive nature. Keratoacanthoma infrequently presents as multiple tumors and may enlarge (5–15 cm), become locally aggressive, and rarely metastasize.

Case presentation

A 66-year-old Arab male patient with diabetes was referred to the Maxillofacial Surgery Department with a chief complaint of a dome-shaped nodule with a smooth, shiny surface and central crateriform ulceration with a keratin plug in the form of a horn-like projection. Skin papules were present in the right lateral canthal area and extended to the lateral border of the lower eyelid, measuring 1.3 cm. On palpation, the lesion was firm, movable, and tender. The patient had a history of a similar lesion in another area of his face that had spontaneously regressed.

Conclusion

Histological differentiation between keratoacanthoma and well-differentiated squamous cell carcinoma is difficult, particularly when a secondary infection is present. Careful establishment of the correlation among the history, clinical findings, and histopathology is highly indicated to avoid unnecessary surgical intervention.

Keratoacanthoma: clinical and histopathologic features of regression

BACKGROUND

The clinical and histopathologic features of regressing keratoacanthomas have not been adequately described in the literature.

OBJECTIVE

"True" keratoacanthomas (ie, squamous tumors with evidence of spontaneous resolution) were studied clinically and histopathologically.

METHODS

Nineteen crateriform tumors with a partial biopsy histopathologically compatible with keratoacanthoma were followed over time for correlation with biologic behavior (ie, regression). Tumors displaying spontaneous resolution, arbitrarily defined as a decrease in size of at least 25%, were categorized as keratoacanthomas.

RESULTS

Seven regressing keratoacanthomas tended to show flattening before a decrease in diameter. Histopathologically, there was variable epidermal hyperplasia with generally prominent hyperkeratosis, retained crateriform architecture, and dermal fibrosis.

LIMITATIONS

This study has a small sample size.

CONCLUSIONS

Regressing keratoacanthomas show persistent crateriform architecture, clinically and histopathologically. Lesions become flatter before decreasing in diameter, and keratinocytes appear banal and lack glassy pink cytoplasm during regression.

Sorafenib-induced premalignant and malignant skin lesions

PURPOSE

To review characteristics of patients who develop premalignant and malignant skin lesions while on sorafenib therapy and discuss implications for subsequent treatment of their primary malignancies.

BACKGROUND

Sorafenib is a newly developed multitargeted protein kinase inhibitor reported to induce a variety of adverse cutaneous effects, rarely including actinic keratoses, keratocanthomas, and squamous cell carcinomas (SCCs).

METHODS

Published reports of individuals who have developed cutaneous lesions demonstrating atypia of the epidermis are reviewed. In addition, a 77-year-old man who developed not only an SCC but also verrucas within one month of taking sorafenib monotherapy for metastatic adenocarcinoma of the lung is described.

RESULTS

Cutaneous lesions develop most commonly in Caucasian men older than 40 years without previous histories of skin cancer, within two weeks to three years of starting sorafenib therapy. Currently there is no definitive explanation for the relationship between sorafenib and cutaneous neoplasms. Management typically involves treatment of skin lesions with cryotherapy or excision with at least a brief discontinuation of sorafenib. In patients whose primary malignancies were responding well, sorafenib therapy was continued with close follow-up.

CONCLUSIONS

The possibility of rapidly developing actinic keratoses, keratocanthomas, verrucas, and SCC during treatment with sorafenib, warrants close dermatologic follow-up and a lower threshold for biopsy and treatment of suspicious cutaneous lesions. Development of a sorafenib-induced SCC is not an absolute contraindication for continued use of sorafenib therapy; however, the drug should be briefly discontinued until lesions are treated.

Keratoacanthoma: facts and controversies

The keratoacanthoma and its variants are clinically and histologically heterogenous. Some consider the keratoacanthoma to be benign, whereas others classify it as a subtype of squamous cell carcinoma. The keratoacanthoma is generally treated rather than observed for spontaneous resolution. This hampers evaluation of the true natural history of lesions diagnosed as keratoacanthoma. In addition, studies have not found a reliable marker to differentiate keratoacanthoma from squamous cell carcinoma. It currently remains unclear how the keratoacanthoma relates to squamous cell carcinoma, and continued investigation is necessary.