Clinical and histological findings in re-excision of incompletely excised cutaneous squamous cell carcinoma

Management of Cutaneous Squamous Cell Carcinoma of the Scalp: The Role of Imaging and Therapeutic Approaches

Cutaneous squamous cell carcinoma (cSCC) is the second most common subtype of skin cancer. The scalp is one of the most frequently affected locations and is associated with a higher rate of complications, compared to other locations. In addition, it has a characteristic thickness and anatomical structure that may influence both growth pattern and treatment of primary cSCC; while clinical peripheral margins may be easily achieved during the surgery, vertical excision of the tumor is limited by the skull. Despite having a unique anatomy, current guidelines do not contemplate specific recommendations for scalp cSCC, which leads to inconsistent decision-making in multidisciplinary committees when discussing tumors with high risk factors or with close margins. This article provides specific recommendations for the management of patients with scalp cSCC, based on current evidence, as well as those aspects in which evidence is lacking, pointing out possible future lines of research. Topics addressed include epidemiology, clinical presentation and diagnosis, imaging techniques, surgical and radiation treatments, systemic therapy for advanced cases, and follow-up. The primary focus of this review is on management of primary cSCC of the scalp with localized disease, although where relevant, some points about recurrent cSCCs or advanced disease cases are also discussed.

Surgical outcomes for cutaneous squamous cell carcinoma of the auricle

Background

Cutaneous squamous cell carcinoma (CSCC) on the auricle is believed to carry a higher risk of metastatic spread. The rates of lymphatic metastasis reported in the literature have varied widely. There are no established prognostic criteria to determine which of these tumors are higher risk and warrant prophylactic treatment of the associated lymphatic basins.

Objective

To retrospectively evaluate outcomes after surgical treatment of auricular CSCC in our department, examining excision completeness, tumor recurrence, and lymphatic metastasis. Secondarily, to identify factors associated with lymphatic metastasis.

Methods

One hundred and thirty-eight consecutive cases of auricular SCC were excised from 126 patients in our department over a 7-year period (January 2012-December 2018). Data were retrospectively collected on patient characteristics, tumor histology, surgical procedures, and follow-up.

Results

Incomplete initial excision occurred in 17 cases (12.32%). Six patients (4.76%) had a local recurrence. Lymphatic metastasis occurred in eight patients (6.35%), on average within 10.25 months after primary excision. Six patients with metastasis died during follow-up, with a mean survival of 10.2 months. Older age was associated with lymphatic metastasis (P = 0.0267). Other factors, including tumor recurrence, size, grade, cartilage invasion, and positive margins, were evaluated and not significantly associated with metastasis.

Conclusion

In this study, the metastatic rate of auricular SCC was 6.35%, which is within the previously reported ranges. No histological prognostic factors were identified in this study, which may be due to our limited sample size. In the absence of established prognostic criteria, decisions regarding prophylactic treatment should be made on an individual basis with multidisciplinary support.

Comparative study of pre- and postauricular flaps for external auditory canal defect reconstruction

BACKGROUND

Malignancies involving the external auditory canal deserve critical evaluation due to this area's aesthetic and functional importance. Flaps can be very useful for the restoration of the external auditory canal. A variety of flaps available for the surgical treatment of external acoustic meatus defects exist, depending on the precise location and size.

OBJECTIVES

Our study aimed to compare aesthetic and functional results in the postoncological reconstruction of external auditory canal defects using a preauricular flap and postauricular revolving door flap.

METHODS

Sixteen patients treated at our plastic surgery unit for defects involving the external auditory canal between January 2014 and December 2020 were included in the study. All defects were the result of a primary or secondary skin cancer excision. Patients were divided into two groups, one receiving the preauricular flap technique and the other the postauricular revolving door flap technique.

RESULTS

Three separate visual analog scales reported excellent scores for the two procedures, though the postauricular revolving door flap had slightly better results. Both preauricular flap and postauricular revolving door flap reconstructive techniques showed good options for external auditory canal reconstruction in postexcision skin cancer patients. From an aesthetic point of view, the revolving door flap appeared to be a more elegant surgical approach in this type of reconstruction because the scar was hidden in the postauricular sulcus.

CONCLUSIONS

Reconstruction with a postauricular revolving door flap allowed for a more natural movement with no external pedicle.

EVIDENCE-BASED MEDICINE EBM LEVEL

IV.

Rate and Characteristics of Incompletely Excised Cutaneous Squamous Cell Carcinoma: A Dermatological Daily Practice Multicenter Prospective Cohort Study

BACKGROUND

Incomplete excision of squamous cell carcinoma (cSCC) is associated with an increased risk of recurrence, metastasis, and mortality.

OBJECTIVE

To determine the rate and characteristics of incompletely excised cSCC in a dermatological daily practice setting.

METHODS

Prospective study of all patients who gave informed consent, with a cSCC treated with standard excision (SE) at 1 of 6 Departments of Dermatology in the Netherlands between 2015 and 2017. Pathological reports were screened to detect all incompletely excised cSCCs.

RESULTS

A total of 592 patients with 679 cSCCs were included, whereby most cases were low risk cSCC (89%). The rate of incompletely excised cSCC was 4% (n = 26), and the majority were high-risk cSCCs of which 24 invaded the deep excision margin.

CONCLUSION

This prospective study showed that in a dermatological setting, the risk of an incompletely excised cSCC is low (4%) for a cohort that was dominated by low-risk cSCCs. Most incompletely excised cSCCs were of high risk, and incompleteness was almost always at the deep margins. These results suggest that for high-risk cSCC, one should pay attention especially to the deep margin when performing SE, and/or microscopic surgery should be considered.

Clinical and Financial Implications of Positive Margins After Nonmelanoma Skin Cancer Resection: A Longitudinal Evaluation

BACKGROUND

Management of positive margins after nonmelanoma skin cancer (NMSC) excision is debated in the literature. The purpose of this study is to determine the rate of residual tumor in reexcised NMSC specimens after previous excision with positive margins, to determine the rate of recurrence in patients who had positive margins but did not undergo reexcision, and to define the financial burden of negative reexcisions.

METHODS

An Institutional Review Board-approved retrospective review was conducted on all patients with NMSC excision over a 15-year period. Patients who met inclusion criteria and underwent initial NMSC excision with negative frozen section margins, but had positive permanent section margins were divided into 2 groups: those who underwent reexcision for clearance of tumor (n = 161) or those who did not undergo further reexcision (n = 105). Variables collected include demographics, previous skin cancer, tumor location, cancer subtype, excision measurements, and time between first and second excisions. For those patients who did not undergo reexcision, charts were examined for recurrence.

RESULTS

Two hundred sixty-six patients met inclusion criteria with mean follow-up of 60 months. Eighty-three (52%) of 161 patients with positive margins on initial excision had no evidence of residual cancer upon reexcision. Residual tumor on permanent section was confirmed in 48% of patients. Patients with a previous history of basal cell carcinoma were more likely to have a true-positive margin after reexcision (P = 0.02). Larger reexcisions were more likely to harbor residual cancer (5.9 cm2, P = 0.04). Patients with positive margins that did not undergo reexcision, only 7 of 105 patients (6.6%) had recurrence. No mortalities were reported from NMSC recurrence. US $247,672 was spent in reexcision for negative margins in 98 patients for an average cost of US $2984 per case.

CONCLUSIONS

Forty-eight percent of NMSC patients with positive margins had residual tumor upon reexcision. There were 6.6% of the patients who did not undergo resection after positive margins developed recurrence of disease at 5 years. Patients requiring larger reexcisions or those with a prior history of BCC were more likely to have residual cancer upon reexcision. This study suggests that observation is an appropriate option of care for certain patients with residual NMSC on permanent pathology.

Incomplete surgical excision of keratinocyte skin cancers: a systematic review and meta‐analysis*

BACKGROUND

Keratinocyte or nonmelanoma skin cancer (NMSC) is the commonest malignancy worldwide. The usual treatment is surgical excision. Current guidelines underestimate incomplete excision rates.

OBJECTIVES

We aimed to determine the risk of incomplete excision of NMSCs through a systematic review and meta-analysis of primary clinical studies.

METHODS

A PRISMA-compliant systematic review and meta-analysis was performed using methodology proposed by Cochrane (PROSPERO CRD42019157936). A comprehensive search strategy was applied to MEDLINE, Embase, Scopus, CINAHL, EMCare, Cochrane Library and the grey literature (January 2000-27 November 2019). All studies were included except those on Mohs micrographic surgery, frozen section or biopsies. Abstract screening and data extraction were performed in duplicate. Risk of bias was assessed using a tool for prevalence/incidence studies. The primary outcome was the proportion of incomplete surgical excisions. A random-effects model for pooling of binomial data was used. Differences between proportions were assessed by subgroup meta-analysis and meta-regression, which were presented as risk ratios (RRs).

RESULTS

Searching identified 3477 records, with 110 studies included, comprising 53 796 patients with 106 832 basal cell carcinomas (BCCs) and 21 569 squamous cell carcinomas (SCCs). The proportion of incomplete excisions for BCC was 11·0% [95% confidence interval (CI) 9·7-12·4] and for SCC 9·4% (95% CI 7·6-11·4). Proportions of incomplete excisions by specialty were: dermatology, BCCs 6·2% and SCCs 4·7%; plastic surgery, BCCs 9·4% and SCCs 8·2%; general practitioners, BCCs 20·4% and SCCs 18·9%. The risk of incomplete excision for general practitioners was four times that of dermatologists for both BCCs (RR 3·9, 95% CI 2·0-7·3) and SCCs (RR 4·8, 95% CI 1·0-22·8). Studies were heterogeneous (I²  = 98%) and at high risk of bias.

CONCLUSIONS

The proportion of incomplete excisions is higher than previously reported. Excisions performed by specialists may lower the risk of incomplete excision.

Poorly differentiated cutaneous squamous cell carcinomas have high incomplete excision rates with UK minimum recommended pre-determined surgical margins

BACKGROUND

In the UK, the British Association of Dermatology-British Association of Plastic, Reconstructive and Aesthetic Surgery (BAD-BAPRAS) guidelines recommend excision of high-risk cutaneous squamous cell carcinomas (cSCCs), including poorly differentiated cSCCs, with a minimum peripheral margin of 6 mm¹.

OBJECTIVES

We assess whether the BAD-BAPRAS minimum margin achieves histological clearance in poorly differentiated cSCCs.

PATIENTS AND METHODS

Demographics, surgical notes and histological reports from all patients having a primary cSCC excised at the Plastic Surgery Department of Addenbrooke's Hospital, Cambridge, UK, between January 2017 and April 2018 were analysed. Ordinal regression was performed for excision margin status versus histological grade by using size and site as co-variates.

RESULTS

Of 296 cSCCs, 38(12.8%) were poorly differentiated. Patients with poorly differentiated cSCCs were older (81.1 years vs. 76.7 years, p = 0.038), had lesions on the face or scalp (89.2% vs. 52.1%, p = 0.0001), and had lymphovascular (10.5% vs. 0%, p = 0.001) or perineural invasion (15.8% vs. 2%, p = 0.002). Well-differentiated cSCCs were excised with an average peripheral margin of 4.72 mm (95% CI 4.25-5.18 mm), while poorly differentiated cSCCs were excised with a margin of 6.42 mm(95% CI 5.58-7.28 mm). Close or involved peripheral margins were seen in 3% of well-differentiated lesions but in 13.2% of poorly differentiated lesions (OR=45.02; p = 0.003). Deep margins were close in 13.1% (none involved) of well-differentiated lesions but close or involved in 50% of poorly differentiated lesions (OR=11.94; p = 0.001).

CONCLUSIONS

We demonstrate that poorly differentiated cSCCs are frequently incompletely excised in both peripheral and deep planes, despite adherence to guidelines. The UK BAD-BAPRAS guidelines should be urgently updated in line with international consensus.

A programme of research to set priorities and reduce uncertainties for the prevention and treatment of skin disease

Background

Skin diseases are very common and can have a large impact on the quality of life of patients and caregivers. This programme addressed four diseases: (1) eczema, (2) vitiligo, (3) squamous cell skin cancer (SCC) and (4) pyoderma gangrenosum (PG).

Objective

To set priorities and reduce uncertainties for the treatment and prevention of skin disease in our four chosen diseases.

Design

Mixed methods including eight systematic reviews, three prioritisation exercises, two pilot randomised controlled trials (RCTs), three feasibility studies, two core outcome initiatives, four funding proposals for national RCTs and one completed national RCT.

Setting

Secondary care, primary care and the general population.

Participants

Patients (and their caregivers) with eczema, vitiligo, SCC and PG, plus health-care professionals with an interest in skin disease.

Interventions

Our three intervention studies included (1) barrier enhancement using emollients from birth to prevent eczema (pilot RCT); (2) handheld narrowband ultraviolet light B therapy for treating vitiligo (pilot RCT); and (3) oral ciclosporin (Neoral®, Novartis Pharmaceuticals) compared with oral prednisolone for managing PG (pragmatic national RCT).

Results

Systematic reviews included two overarching systematic reviews of RCTs of treatments for eczema and vitiligo, an umbrella review of systematic reviews of interventions for the prevention of eczema, two reviews of treatments for SCC (one included RCTs and the second included observational studies), and three reviews of outcome measures and outcome reporting. Three prioritisation partnership exercises identified 26 priority areas for future research in eczema, vitiligo and SCC. Two international consensus initiatives identified four core domains for future eczema trials and seven core domains for vitiligo trials. Two pilot RCTs and three feasibility studies critically informed development of four trial proposals for external funding, three of which are now funded and one is pending consideration by funders. Our pragmatic RCT tested the two commonly used systemic treatments for PG (prednisolone vs. ciclosporin) and found no difference in their clinical effectiveness or cost-effectiveness. Both drugs showed limited benefit. Only half of the participants’ ulcers had healed by 6 months. For those with healed ulcers, recurrence was common (30%). Different side effect profiles were noted for each drug, which can inform clinical decisions on an individual patient basis. Three researchers were trained to PhD level and a dermatology patient panel was established to ensure patient involvement in all aspects of the programme.

Conclusions

Findings from this programme of work have already informed clinical guidelines and patient information resources. Feasibility studies have ensured that large national pragmatic trials will now be conducted on important areas of treatment uncertainty that address the needs of patients and the NHS. There is scope for considerable improvement in terms of trial design, conduct and reporting for RCTs of skin disease, which can be improved through wider collaboration, registration of trial protocols and complete reporting and international consensus over core outcome sets. Three national trials have now been funded as a result of this work. Two international initiatives to establish how best to measure the core outcome domains for eczema and vitiligo are ongoing.

Trial registration

Current Controlled Trials Barrier Enhancement for Eczema Prevention (BEEP) (ISRCTN84854178 and NCT01142999), Study of Treatments fOr Pyoderma GAngrenosum Patients (STOP GAP) (ISRCTN35898459) and Hand Held NB-UVB for Early or Focal Vitiligo at Home (HI-Light Pilot Trial) (NCT01478945).

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 4, No. 18. See the NIHR Journals Library website for further project information.

The Effect of Differentiation Grade of Cutaneous Squamous Cell Carcinoma on Excision Margins, Local Recurrence, Metastasis, and Patient Survival: A Retrospective Follow-Up Study

BACKGROUND

The incidence of cutaneous squamous cell carcinoma (SCC) is increasing worldwide. Despite a growing body of literature on prognostic factors, it remains unclear how tumor differentiation grade influences patient survival. The aim of this study was to investigate a possible correlation between cutaneous SCC differentiation, local recurrence, metastasis, and patient survival.

MATERIALS AND METHODS

All consecutive patients treated for cutaneous SCC between 2001 and 2008 were retrospectively analyzed. Univariate survival analysis was used to assess the association of different tumor characteristics with survival.

RESULTS

One hundred thirty-one patients with 155 SCCs were included (median follow-up, 81 months; range, 27-125 months). Although no significant correlation between tumor differentiation grade and local recurrence could be found, it was an independent prognostic factor for metastatic disease and overall survival (OS). Metastasis-free survival at 5 years was significantly higher in well-differentiated tumors (70%) compared to moderately (51%) and poorly differentiated SCCs (26%; P = 0.012); identical percentages were found for OS (P = 0.005). Furthermore, patients with incomplete excision of the first tumor showed an increased relative risk of dying of SCC of 4.0 (95% confidence interval, 2.4-6.6; P < 0.001) compared to excision with clear margins.

CONCLUSIONS

Studies that investigated the relationship between SCC differentiation grade and patient survival are scarce and inconsistent. The present study indicates tumor differentiation grade is an independent prognostic factor for OS. This finding suggests poor differentiation of cutaneous SCC alone is sufficient to upstage the primary tumor in the TNM classification system.

[Squamous cell carcinomas of the ear: factors of gravity and surgical treatment, about 30 cases]

INTRODUCTION

Squamous cell carcinomas (SCC) of the ear are known for their aggressiveness. The aim of this study was to investigate factors of gravity while freeing the therapeutic requirements.

PATIENTS AND METHODS

This is a retrospective study of 28 patients (30 ears) operated for SCC. The characteristics of the lesion, the presence of metastasis, treatment modalities and histologic findings were collected. Local recurrences and metastasis are identified with a mean follow-up time of 37months (17-110months).

RESULTS

The lesion size was less than 2cm in 19 cases (63.3%) and greater than or equal to 2cm in 11 cases (36.7%). Macroscopic resection margins were 5, 7 or 10mm. The resections were histologically incomplete in 4 cases (13%) requiring further surgery. Six cases had local recurrence (20%): three with pulmonary or lymph node metastases (10%) and one death (3.3%). In these 6 cases of recurrence, the surgical margins were 6.3mm on average, the initial lesion measured always greater than 2cm (100%). Three quarters of incomplete resections have recurrent despite a surgical revision in healthy margin.

CONCLUSION

Our study confirms the data of literature, namely the pejorative character of a lesion greater than 2cm and incomplete resection. The HAS recommendations seem minimal regarding the ear. In case of injury by more than 2cm and with a proximal location on the ear pinna, only amputation of the ear allows satisfactory cancer control.

Interventions for non-metastatic squamous cell carcinoma of the skin: systematic review and pooled analysis of observational studies

OBJECTIVES

To assess the effects of treatments for non-metastatic invasive squamous cell carcinoma (SCC) of the skin using evidence from observational studies, given the paucity of evidence from randomised controlled trials.

DESIGN

Systematic review of observational studies.

DATA SOURCES

Medline, Embase, to December 2012.

REVIEW METHODS

Observational studies of interventions for primary, non-metastatic, invasive, SCC of the skin that reported recurrence during follow-up, quality of life, initial response to treatment, adverse events, cosmetic appearance, or death from disease. Studies were excluded if data for primary cutaneous SCC was not separable from other data. Data were extracted independently by two reviewers. Meta-analysis was performed where appropriate using a random effects model to estimate the pooled proportion of an event with 95% confidence intervals.

RESULTS

118 publications were included, covering seven treatment modalities. Pooled estimates of recurrence of SCCs were lowest after cryotherapy (0.8% (95% confidence interval 0.1% to 2%)) and curettage and electrodesiccation (1.7% (0.5% to 3.4%)), but most treated SCCs were small, low risk lesions. After Mohs micrographic surgery, the pooled estimate of local recurrence during variable follow-up periods from 10 studies was 3.0% (2.2% to 3.9%), which was non-significantly lower than the pooled average local recurrence of 5.4% (2.5% to 9.1%) after standard surgical excision (12 studies), and 6.4% (3.0% to 11.0%) after external radiotherapy (7 studies). After an apparently successful initial response of SCCs to photodynamic therapy, pooled average recurrence of 26.4% (12.3% to 43.7%; 8 studies) was significantly higher than other treatments. Evidence was limited for laser treatment (1 study) and for topical and systemic treatments (mostly single case reports or small non-comparative series with limited follow-up).

CONCLUSIONS

Many observational studies have looked at different treatment modalities for SCC, but the evidence base for the effectiveness of these interventions is poor. Comparison of outcomes after different treatments should be interpreted cautiously owing to biases inherent in the types of study included, and lack of direct comparisons to enable the estimation of relative treatment effect. Further evidence is needed to develop a prognostic model and stratify individuals at high risk of developing SCC, to improve the evidence base for this common cancer and to optimise clinical management.

PROTOCOL REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO) registration number CRD42011001450.

Nonmelanoma skin cancer of the head and neck: surgical treatment

This article focuses on the surgical treatment of nonmelanoma skin cancers of the head and neck. The risk factors of nonmelanoma skin cancers for recurrence and metastases that are important for choosing the best treatment option are summarized. Surgical treatment options including surgical excision with standard margins, frozen section, staged surgery, and Mohs micrographic surgery are described. Indications, techniques, outcomes, and advantages and disadvantages of each approach are reviewed. Finally, management of incomplete excisions is discussed.

Guidelines for the excision of cutaneous squamous cell cancers in the United Kingdom: the best cut is the deepest

Surgical excision remains the gold standard for the management of cutaneous squamous cell cancers (SCC) and national guidelines for operative radial margins predict 95% oncological clearance with a margin of 4 mm for low-risk and 6 mm for high-risk tumours. We retrospectively analysed all cutaneous SCC excisions performed across 4 regional Plastic surgical units in England over a consecutive 24-month period and collected data on tumour characteristics, operative and histological margins and completeness of excision. We identified 633 eligible SCC excisions of which 265 (42%) were over 2 cm in diameter with 37 recurrent tumours (5.8%). The mean radial operative margin was 6.5 mm across all tumours and 8.4 mm for tumours greater than 2 cm. The mean histological tumour diameter was 21 mm. The overall incomplete excision rate was 7.6% (7.9% for tumours >2 cm). Ninety-four percent (45/48) of incomplete excisions involved the deep margin and only 3 out of 633 excisions (0.47%) were incomplete at a radial margin only. No differences were observed in tumour size or excision margin between incompletely and completely excised tumours. Incomplete excisions were most common on the ear, nose and cheek. In summary our analysis demonstrates that despite adherence to recommended surgical margins for cutaneous SCCs the incomplete excision rate remains higher than expected. We believe that this is because most incomplete excisions are incomplete at the deep margin and question the utility of performing increasingly wide excisions, and, the generalisability of the evidence upon which recommendations for radial margins are based.

Identification of the optimal therapeutic antibody for fluorescent imaging of cutaneous squamous cell carcinoma

Intraoperative, real-time fluorescence imaging may significantly improve tumor visualization and resection and postoperatively, in pathological assessment. To this end, we sought to determine the optimal FDA approved therapeutic monoclonal antibody for optical imaging of human cutaneous squamous cell carcinoma (cSCC). A near-infrared (NIR) fluorescent probe (IRDye800) was covalently linked to bevacizumab, panitumumab or tocilizumab and injected systemically into immunodeficient mice bearing either cutaneous tumor cell lines (SCC13) or cutaneous human tumor explants. Tumors were then imaged and resected under fluorescent guidance with the SPY, an FDA-approved intraoperative imaging system, and the Pearl Impulse small animal imaging system. All fluorescently labeled antibodies delineated normal tissue from tumor in SCC13 xenografts based on tumor-to-background (TBR) ratios. The conjugated antibodies produced TBRs of 1.2-2 using SPY and 1.6-3.6 using Pearl; in comparison, isotype control antibody IgG-IRDye produced TBRs of 1.0 (SPY) and 0.98 (Pearl). Comparison between antibodies revealed them to be roughly equivalent for imaging purposes with both the SPY and Pearl (p = 0.89 SPY, p = 0.99 Pearl; one way ANOVA). Human tumor explants were also imaged and tumor detection was highest with panitumumab-IRDye800 when using the SPY (TBR 3.0) and Pearl (TBR 4.0). These data suggest that FDA approved antibodies may be clinically used for intraoperative detection of cSCC.

Rapid screening of cancer margins in tissue with multimodal confocal microscopy

BACKGROUND

Complete and accurate excision of cancer is guided by the examination of histopathology. However, preparation of histopathology is labor intensive and slow, leading to insufficient sampling of tissue and incomplete and/or inaccurate excision of margins. We demonstrate the potential utility of multimodal confocal mosaicing microscopy for rapid screening of cancer margins, directly in fresh surgical excisions, without the need for conventional embedding, sectioning, or processing.

MATERIALS AND METHODS

A multimodal confocal mosaicing microscope was developed to image basal cell carcinoma margins in surgical skin excisions, with the resolution that shows nuclear detail. Multimodal contrast is with fluorescence for imaging nuclei and reflectance for cellular cytoplasm and dermal collagen. Thirty-five excisions of basal cell carcinomas from Mohs surgery were imaged, and the mosaics analyzed by comparison with the corresponding frozen pathology.

RESULTS

Confocal mosaics are produced in about 9 min, displaying tissue in fields of view of 12 mm with ×2 magnification. A digital staining algorithm transforms black and white contrast to purple and pink, which simulates the appearance of standard histopathology. Mosaicing enables rapid digital screening, which mimics the examination of histopathology.

CONCLUSIONS

Multimodal confocal mosaicing microscopy offers a technology platform to potentially enable real-time pathology at the bedside. The imaging may serve as an adjunct to conventional histopathology to expedite screening of margins and guide surgery toward more complete and accurate excision of cancer.

Confocal mosaicing microscopy of human skin ex vivo: spectral analysis for digital staining to simulate histology-like appearance

Confocal mosaicing microscopy enables rapid imaging of large areas of fresh tissue, without the processing that is necessary for conventional histology. Mosaicing may offer a means to perform rapid histology at the bedside. A possible barrier toward clinical acceptance is that the mosaics are based on a single mode of grayscale contrast and appear black and white, whereas histology is based on two stains (hematoxylin for nuclei, eosin for cellular cytoplasm and dermis) and appears purple and pink. Toward addressing this barrier, we report advances in digital staining: fluorescence mosaics that show only nuclei, are digitally stained purple and overlaid on reflectance mosaics, which show only cellular cytoplasm and dermis, and are digitally stained pink. With digital staining, the appearance of confocal mosaics mimics the appearance of histology. Using multispectral analysis and color matching functions, red, green, and blue (RGB) components of hematoxylin and eosin stains in tissue were determined. The resulting RGB components were then applied in a linear algorithm to transform fluorescence and reflectance contrast in confocal mosaics to the absorbance contrast seen in pathology. Optimization of staining with acridine orange showed improved quality of digitally stained mosaics, with good correlation to the corresponding histology.