Rapid cytokeratin stains enhance the sensitivity of Mohs micrographic surgery for squamous cell carcinoma

Aggressive Cutaneous Squamous Cell Carcinoma of the Head and Neck: A Review

Non-melanoma skin cancer of the head and neck (NMSCHN) is one of the most common malignancies worldwide, and its incidence is growing at a significant rate. It has been found to be aggressive in its spread and has the capacity to metastasize to regional lymph nodes. Cutaneous squamous cell carcinoma (cSCC) has a considerably high mortality rate. It has remarkable characteristics: diameter >2 cm, depth >5 mm, high recurrence, perineural invasion, and locoregional metastases. Aggressive cSCC lesions most commonly metastasize to the parotid gland. Also, immunocompromised patients have a higher risk of developing this aggressive cancer along with the worst prognostic outcomes. It is very important to discuss and assess the risk factors, prognostic factors, and outcomes of patients with cSCC, which will give clinicians future directives for making modifications to their treatment plans. The successful treatment of aggressive cSCC of the head and neck includes early detection and diagnosis, surgery alone or adjuvant chemotherapy, and radiotherapy as required. Multimodal therapy options should be considered by clinicians for better outcomes of aggressive cSCC of the head and neck.

Use of a novel 1-hour protocol for rapid frozen section immunocytochemistry, in a case of squamous cell carcinoma treated with Mohs micrographic surgery

For squamous cell carcinoma (SCC) treated using Mohs micrographic surgery (MMS), interpretation of haematoxylin and eosin-stained frozen sections can be challenging. In these situations, ancillary use of immunostaining is a useful tool for the Mohs surgeon. However, use of immunostaining in MMS laboratories is limited, mainly because current manual immunostaining platforms are subject to operator error, and automated immunostaining, albeit accurate, is too slow for inclusion in MMS. In this report, we describe a novel 1-hour protocol for rapid frozen section immunocytochemistry, using the pancytokeratin markers AE1/AE3. This protocol has been specifically designed to integrate the speed of manual techniques and the accuracy of automated platforms, making it a valuable addition to the MMS laboratory. We propose that in selected or histologically challenging cases, there is a role for the use of this novel protocol, allowing the Mohs surgeon to more confidently declare tumour clearance, thus preventing further unnecessary surgery and preserving healthy tissue.

Pan-cytokeratin markers for rapid frozen section immunocytochemistry from head and facial Mohs cases of basal cell carcinoma: a comparison and evaluation to determine the marker of choice

The application of immunocytochemistry in the field of Mohs micrographic surgery (MMS) is well established. This study evaluates the use of pan-cytokeratins (AE1/AE3, MNF116 and AE1/AE3+PCK26) in the assessment of basal cell carcinoma (BCC) on frozen tissue debulk specimens. Fifty-five cases of BCC, all from head and facial sites, were assessed in the study. In addition to staining all cases for the three cytokeratin antibodies under investigation, sections were also stained with haematoxylin and eosin (H&E) to demonstrate tumour architecture and morphology. All sections for immunocytochemistry were stained on a Roche Ventana BenchMark Ultra automated platform employing a rapid frozen section protocol. Results were assessed based on the intensity of staining of keratinocytes (scale: 0-100%), as well as sensitivity of staining determined by the total percentage of keratinocytes stained within the tissue section. AE1/AE3 demonstrated the most consistent staining both in terms of intensity of staining and sensitivity, with a mean of 99.1% and 99.9%, respectively. AE1/AE3+PCK26 average results indicated scores of 70.6% for intensity and 87.2% for sensitivity, with MNF116 scoring 92.9% for intensity but only 57.3% for sensitivity. The data indicate that AE1/AE3 is the best pan-cytokeratin antibody to use in the assessment of BCC in MMS. The use of cytokeratin immunocytochemistry is justified in morphologically complex cases of BCC, or in cases where dense inflammatory infiltrate surrounding any suspicious cells make identification of small numbers of tumour cells difficult to determine with just an H&E stain. The significant rationale is that cytokeratin staining is a valuable adjunct in the study of tumour cell assessment in cases of MMS for BCC. In addition, the use of anti-AE1/AE3 cytokeratin antibodies provides the most consistent staining results for such cases.

Mohs frozen tissue sections in comparison to similar paraffin-embedded tissue sections in identifying perineural tumor invasion in cutaneous squamous cell carcinoma

BACKGROUND

Perineural invasion (PNInv) in cutaneous squamous cell carcinoma (cSCC) increases the risk of recurrence, possibly because of suboptimal identification on frozen or paraffin-embedded tissue sections. Perineural inflammation (PNInf) may portend PNInv.

OBJECTIVE

We sought to correlate identification of PNInv and PNInf in hematoxylin-eosin-stained Mohs frozen sections with PNInv and PNInf identified in similarly oriented paraffin-embedded sections obtained in cases of cSCC.

METHODS

We reviewed same patient Mohs frozen and paraffin-embedded tissue sections for all patients presenting within a 2-year period to our Mohs micrographic surgical unit for removal of cSCC with PNInv or PNInf identified on either type of tissue section.

RESULTS

Of 537 patients undergoing surgical resection of cSCC, 21 (3.9%) had either PNInv (n = 11) or PNInf (n = 10) on frozen sections. PNInv on Mohs frozen sections was identified in 11 cases and confirmed on paraffin-embedded sections in 9 cases (82%). Paraffin-embedded sections failed to identify PNInv present in Mohs frozen sections in two (2/11), or 18% of cases. PNInf on Mohs frozen sections was confirmed on paraffin-embedded sections in 3 cases (30%), but PNInv was identified in 5 cases (50%).

LIMITATIONS

Our results are a retrospective case review from a specific time period by one institution. Furthermore, it is impossible to compare identical tissue specimens using two sequential tissue processing techniques.

CONCLUSION

PNInv can be accurately identified with Mohs frozen sections. PNInf on Mohs frozen sections suggests the presence of PNInv and requires further histologic investigation.

Special stains in Mohs surgery

The excellent cure rates associated with Mohs micrographic surgery depend on accurate interpretation of complete and high-quality microscopic frozen sections. Reliable interpretation of microscopic slides is only possible if the surgeon can distinguish tumor cells from surrounding normal tissue. By highlighting tumor cells with a chromogen that is visible on light microscopy, immunostaining allows the Mohs surgeon to distinguish tumor from normal cells in these challenging scenarios. This article focuses on practical aspects involving the most commonly used immunostains in dermatologic surgery, including MART-1 for melanocytic neoplasms, cytokeratin stains for keratinocytic neoplasms, and CD34 stains for dermatofibrosarcoma protuberans.

Immunostaining in Mohs micrographic surgery: a review

BACKGROUND

With the advent of incorporating the immunoperoxidase staining technique into the processing of frozen tissue, the use of Mohs micrographic surgery (MMS) has been expanded to include several high-risk tumors such as lentigo maligna, malignant melanoma, and dermatofibrosarcoma protuberans.

OBJECTIVES

To thoroughly review the English medical literature pertaining to the use of immunohistochemical staining techniques on frozen sections during MMS and to summarize the basic relevant outcomes from the different relevant studies.

MATERIALS AND METHODS

Medline search was conducted, with the following words used in the search criteria: "Mohs surgery,""staining,""immunostaining," and "immunoperoxidase." RESULTS Generally, all immunostains showed advantage over the traditional hematoxylin and eosin approach. Studies of MART-1 in melanoma chemosurgery indicated that it is typically crisp and has less background staining than MEL-5 and better staining consistency than HMB-45. In cases of desmoplastic melanomas, S100 is the stain of choice.

CONCLUSION

Immunostaining offers an advantage in MMS. Large, randomized, prospective studies comparing the different immunostains are still lacking in the literature. The authors have indicated no significant interest with commercial supporters.

Mohs micrographic surgery for the management of nonmelanoma skin cancers

Many treatment modalities have been described to address the growing epidemic of nonmelanoma skin cancer (NMSC). Mohs micrographic surgery (MMS) is a surgical technique that allows complete and precise microscopic margin analysis by using horizontal frozen sections. The purpose of MMS is twofold: to ensure definitive excision and to minimize loss of normal surrounding tissue. MMS offers the advantages of superior cure rates and, because tissue removal is minimized, excellent cosmetic outcomes. Therefore, MMS has become the treatment of choice for many high-risk tumors. Because this technique is labor intensive, MMS is not indicated in certain situations. Understanding the indications, advantages, and disadvantages of MMS remains paramount for facial plastic surgeons managing NMSC.

Current progress of immunostains in Mohs micrographic surgery: a review

Mohs micrographic surgery is often considered the treatment of choice for a variety of skin malignancies. In recent years, the application of immunostaining techniques has facilitated the successful removal of a number of common and less common cutaneous malignancies, including basal cell carcinoma, squamous cell carcinoma, malignant melanoma, dermatofibrosarcoma protuberans, microcystic adnexal carcinoma, sebaceous carcinoma, atypical fibroxanthoma, extramammary Paget's disease, and even sarcomas. Immunostains highlight the tumor cells and allow the Mohs surgeons to pinpoint and eliminate the residual tumor at the surgical margin. It is especially helpful when a tumor presents with subtle or nonspecific histologic features or when a tumor is masked in a pocket of dense inflammation. However, the cost, the labor, and the time consumption are of concern to many of our peers, as are the diversity of antigens, which may overwhelm some. This article serves as a review of the literature on current uses of immunostaining in Mohs micrographic surgery and as a summary of their realistic applications in the dermatologic surgeon's practice. We conclude that immunohistochemical technique has played an important role in Mohs surgery advancement. With greater use and more cost-effective staining methods, we believe that the use of immunostains in a Mohs practice will become routine.

Non-Hodgkin lymphoma and skin cancer: A dangerous combination

There is a significant association between non-Hodgkin lymphoma, including chronic lymphocytic leukaemia, and both melanoma and non-melanoma skin cancer. This review highlights the existing data on the phenomenon of accelerated skin cancer in patients with non-Hodgkin lymphoma and specifically chronic lymphocytic leukaemia. The outcomes of patients with non-Hodgkin lymphoma (including chronic lymphocytic leukaemia) and non-melanoma skin cancer are worse than in patients without concomitant lymphoreticular malignancy, as shown by increased rates of local recurrence, regional metastasis and death. Pathogenic factors may be common between non-Hodgkin lymphoma and chronic lymphocytic leukaemia and skin cancer. The treatment of skin cancer in patients with non-Hodgkin lymphoma must factor in the worse prognosis and adapt standard therapeutic approaches to minimize the risk of metastasis and death. Preventive strategies and early detection are paramount in this high-risk population.

Frozen section of skin specimens

CONTEXT

Skin cancers are the most common malignancies in this country. Treatment of these tumors often involves assessment of margins, which may be performed by frozen section.

OBJECTIVE

This article discusses indications for frozen section, various approaches to gross examination of specimens, Mohs micrographic surgery, diagnostic pitfalls, methods to improve diagnostic accuracy, and special techniques.

DATA SOURCES

The authors' extensive experience and review of the published literature.

CONCLUSIONS

Frozen sections play a vital role in the evaluation of margins of basal cell carcinomas and squamous cell carcinomas. The role of frozen sections in evaluation of soft tissue tumors is controversial. With rare exception, they have no role in the evaluation of melanocytic tumors.

Surgical Margins in the Treatment of Nonmelanoma Skin Cancer and Mohs Micrographic Surgery

Traditional surgical treatment of nonmelanoma skin cancer includes excision with subsequent evaluation of surgical margins, either via frozen sections intraoperatively or after excision and closure. Accurate communication between surgeon and pathologist regarding the meaning of surgical margins should be confirmed. Recurrences of tumor growth may in part be attributed to asymmetrical tumor growth patterns with extension of tumor in an unanticipated direction. Mohs micrographic surgery is an outpatient procedure that maximizes surgical margin evaluation while minimizing the amount of tissue that must be excised. This article will discuss the concept of surgical margins in excisions of nonmelanoma skin cancer and the role of Mohs micrographic surgery.

Ultrarapid Staining for Cutaneous Melanoma

BACKGROUND

Immunohistochemistry has revolutionized the use of frozen sections for the removal of melanoma.

OBJECTIVE

Two studies were performed to address the best and fastest way to stain melanocytes in frozen tissue sections.

MATERIALS AND METHODS

Fifty-six standing cones were taken from sun-damaged white skin and stained with combinations of anti-S-100, anti-HMB-45, anti-Melan-A, and azure B with appropriate controls.

RESULTS

Anti-Melan-A was the best immunohistochemical stain. Azure B stains melanin granules metachromatically green and allows differentiation of melanocytes and melanophages. Ultrarapid staining worked as well as rapid staining.

CONCLUSION

Dako's EnVision ultrarapid staining protocol and azure B counterstain represent a dramatic improvement and should be considered the easily obtainable histologic standard when excising cutaneous melanoma.

Preparation of frozen sections

BACKGROUND

For dermatologists the preparation of frozen sections means micrographic surgery. The preparation of frozen sections is meant to be rapid, but has multiple, discrete steps that demand attention to detail.

OBJECTIVE

The objective was to summarize both the proven and the cutting-edge techniques of frozen section preparation.

MATERIALS AND METHODS

Reports from the medical literature were used to augment techniques used in our practices.

CONCLUSION

We dissect each step of micrographic cancer removal, report on the standard and preferred methods of tissue preparation, and summarize the progress achieved in the past decade.

Adjuvant cytokeratin staining in Mohs micrographic surgery for basal cell carcinoma

BACKGROUND

Mohs micrographic surgery (MMS) is a technique that offers excellent cure rates in the treatment of basal cell carcinoma (BCC). One of the reasons for its success is the 100% visualization of the resection margins. Still, recurrences do occur in 2% to 5% of the treated BCCs. It has been suggested that BCC cells in frozen sections stained with hematoxylin and eosin (H&E) may be missed.

OBJECTIVE

To determine whether an additional immunohistochemical staining with a cytokeratin marker (MNF 116) indicates BCC cells in sections in which the H&E-stained frozen sections were negative.

METHODS

The Mohs procedure was performed under standard conditions in which H&E-stained slides were judged by the Mohs surgeon and the pathologist. After the H&E slides where judged negative, an extra slide was stained using immunohistochemistry and a monoclonal antibody against cytokeratin (MNF 116).

RESULTS

A total of 143 complete slides were stained and judged by two Mohs surgeons and a pathologist. One of the 143 slides stained with MNF 116 showed positive staining where the H&E slides were negative, which is 0.7% of the slides. However, this single slide represents a failure of nearly 2% of the treated patients.

CONCLUSION

Frozen sections stained with H&E in MMS offer enough security in detecting BCC cells during surgery; however, adjuvant cytokeratin staining can be useful in very selected cases of aggressive growing BCC.

Immunohistochemical staining of lentigo maligna during Mohs micrographic surgery using MART-1

BACKGROUND

Lentigo maligna (LM) often displays extensive subclinical spread. Mohs micrographic surgery (MMS) has been proposed to help delineate the true histologic margin; however, visualizing atypical melanocytes on frozen section is challenging and often requires confirmatory permanent paraffin sections.

OBJECTIVE

Our aim was to use a monoclonal antibody to rapidly stain frozen sections during MMS to facilitate better visualization of atypical melanocytes.

METHODS

Frozen sections of LM during MMS were stained with MART-1 (melanoma antigen recognized by T cells) and compared with paraffin-embedded sections.

RESULTS

We found 100% correlation between frozen sections stained with MART-1 and paraffin-embedded sections.

CONCLUSIONS

Atypical melanocytes can be better visualized on frozen sections of LM by using MART-1 rather than hematoxylin and eosin. This allows for easier identification during MMS and better chance of complete removal of LM lesions.

Current histologic preparation methods for Mohs micrographic surgery

BACKGROUND

Recently Mohs micrographic surgery, which is widely used for the removal of nonmelanoma skin cancers, has been used to remove lentigo maligna with both rush permanent sections and frozen sections. Several investigators have incorporated the use of immunohistochemical techniques to aid in the interpretation of the specimens.

OBJECTIVE

To determine the current practices of Mohs surgery laboratories, including the use of immunostains and automation of laboratory processes.

METHODS

A total of 108 laboratories responded to a written questionnaire with 13 items about the types of tumors resected, routine stains performed, average number of slides processed per day, and use of automation and immunostains.

RESULTS

Forty-nine percent of the laboratories are completely manual and 51% are automated. The Linistainer automated system, which is the predominant one used, decreased processing time by about 30% and provided an estimated 21-30% improved quality. Automation was associated with the number of slides processed. Immunostaining is performed by a limited number of laboratories which use the technique for basal and squamous cell carcinoma, lentigo maligna, and dermatofibrosarcoma protuberans.

CONCLUSION

Automation of routine slide preparation with a Linistainer decreased staining variability by providing a consistent environment, and decreased processing time. Most laboratories do not perform immunostaining. The relatively high cost of reagents, lack of a reliable automated process, the additional time to process specimens, and the additional technician and physician time makes the procedure impractical for many laboratories.

Current concepts: the use of immunoperoxidase techniques in mohs micrographic surgery

Mohs micrographic surgery is used for the removal of certain malignant tumors, both ensuring complete excision by histologic examination of margins as well as minimizing normal tissue loss. Recently, several investigators have incorporated the use of immunoperoxidase techniques to aid in the removal of selected high-risk carcinomas, sarcomas, and melanomas. We describe the basic principles of immunoperoxidase and review recent articles in which immunoperoxidase was used as an adjunct to routine hematoxylin-eosin staining in Mohs micrographic surgery. Additionally, we show examples of selected tumors comparing routine hematoxylin-eosin stains and immunoperoxidase. We believe the use of immunoperoxidase can be of significant value in the removal of certain high-risk tumors. In particular, this technique is useful in "unmasking" malignant cells in areas of dense inflammation, identification of some cases of perineural invasion, identification of pagetoid spread in carcinomas and melanomas, and finally in helping to identify subtle margins in dermatofibrosarcoma protuberans.

Ber-EP4-positive phenotype differentiates actinic keratosis from superficial basal cell carcinoma

BACKGROUND

Well-defined histopathologic criteria exist to distinguish actinic keratosis (AK) from superficial basal cell carcinoma (BCC). A similar morphology of downwardly budding dysplastic keratinocytes may occur in both entities, creating potential for errors in diagnosis. A marker that could reliably distinguish these two lesions would overcome this difficulty in diagnosis.

OBJECTIVE

To investigate whether Ber-EP4 staining is useful in distinguishing AK from superficial BCC, and to determine whether AK exhibits a cellular phenotype that is more consistent with BCC or squamous cell carcinoma (SCC).

METHODS

We subjected tissue sections from superficial BCC, AK, and squamous intraepithelial neoplasia (SIN) demonstrating epidermal budding to immunohistochemical staining with monoclonal antibody Ber-EP4.

RESULTS

Abnormal keratinocytes in all specimens of superficial BCC (5 of 5) were Ber-EP4 positive; all AK (10 of 10) and SIN (8 of 8) were Ber-EP4 negative.

CONCLUSION

Ber-EP4 staining reliably distinguishes AK from superficial BCC. The lack of Ber-EP4 staining of AK supports the currently accepted pathogenetic dogma that SIN and SCC arise from AK, but BCC does not.

Mohs micrographic surgery

Mohs micrographic surgery (MMS) is a specialized type of minimal marginal surgery that offers cure rates superior to other options in the treatment of contiguous skin cancers in selected settings. Developed by Dr. Frederic E. Mohs, the technique originally required in situ tissue fixation before excision. Most Mohs micrographic surgeons now use the fresh tissue technique exclusively. Horizontal frozen histologic sections of the excised tumor permit more complete microscopic examination of the surgical margin than traditional methods. Residual tumor is graphically mapped and malignant extensions are pursued with staged excisions until the tumor is removed. Maximum sparing of tumor-free adjacent tissue is achieved with histologic mapping of the tumor boundaries, thus optimizing subsequent wound reconstruction. The history, techniques, indications, cure rates, and current controversies of MMS are reviewed.

Squamous cell carcinoma in a patient with chronic lymphocytic leukemia. An intraoperative diagnostic challenge for the Mohs surgeon

BACKGROUND

Chronic lymphocytic leukemia (CLL) is the most common form of chronic leukemia in the US. CLL patients have an increased risk of developing other malignant neoplasms, especially skin cancer. Lymphoma-associated squamous cell carcinomas (SCCs) tend to behave more aggressively and therefore are often treated with Mohs micrographic surgery (MMS).

OBJECTIVE

To elucidate the potential difficulty of distinguishing perineural infiltrates as leukemic infiltrates versus inflammatory infiltrates associated with SCC on frozen tissue sections during MMS.

METHODS

This is a case report illustrating a patient with CLL who develops a SCC on the posterior ear. MMS was employed to treat the patient. Special immunohistochemical stains were performed to help distinguish the type of perineural infiltrate present.

RESULTS

The perineural infiltrate was shown by immunohistochemistry to be leukemic in origin. Special stains for keratin revealed no residual SCC hidden in the infiltrate.

CONCLUSION

CLL is a malignancy that primarily effects the elderly population and markedly increases their risk of developing skin cancers, especially SCC. An intense infiltrate may be present surrounding the tumor. This case report demonstrates one of the potential challenges the Mohs surgeon may face in interpreting histologic frozen section. Immunohistochemistry may be helpful in providing a more definitive answer to this problem.

Anti-human epithelial antigen (Ber-EP4) helps define basal cell carcinoma masked by inflammation

BACKGROUND

Anti-human epithelial antigen (Dako-Ber-EP4) is an antibody raised in mice that reacts with two glycoproteins of 34 and 49 kD. These glycoproteins are present on the cell surface and in the cytoplasm of basal cell carcinoma (BCC) cells, sweat glands, and some hair follicles in the skin.

METHODS

We selected 27 BCCs (15 nodular, 11 morpheic/infiltrative, and one adenoid) and one trichoblastoma and performed rapid immunohistochemical studies with Ber-EP4 and a labeled streptavidin biotin alkaline phosphatase system.

RESULTS

Twenty-seven of 27 BCCs and one of one trichoblastoma were positive for Ber-EP4. Thirteen of 27 BCCs stained with Ber-EP4 showed areas of BCC in dense inflammation that were better defined by the Ber-EP4 immunostain than by the H&E stain. In two cases persistent infiltrative BCC was found in the final Mohs margins while appearing negative with routine H&E. Several instances occurred where negative Ber-EP4 in inflammatory fields resulted in tissue sparing with the avoidance of a further Mohs (insurance) layer.

CONCLUSION

In conclusion, we found mouse anti-human Ber-EP4 a useful and reliable marker for BCC. This antibody helps to locate latent BCC tumor in inflammatory Mohs margins.

The use of monoclonal antibody stains in Mohs micrographic surgery

The recent application of monoclonal antibody stains to Mohs micrographic surgery may lead to increased accuracy in the excision of certain difficult tumours. Immunohistochemical techniques may also increase the range of tumours regularly treated by Mohs surgery. The concept is very much in its infancy, and controlled trials with long-term follow-up are required before the real worth of the process can be evaluated.

Excision of selected skin tumours using Mohs' micrographic surgery with horizontal paraffin-embedded sections

Histological interpretation of frozen sections made during Mohs' micrographic surgery may be difficult, depending on the morphological and staining characteristics of the tumour and on the nature of the associated inflammatory infiltrate. We have employed an adaptation of micrographic surgery in which horizontal, formalin-fixed, paraffin-embedded sections were used to improve histological assessment in the excision of 18 non-melanoma skin tumours in which frozen sections had been or were likely to be unsatisfactory. We describe our experience of this method in the management of squamous cell carcinomas (11), extramammary Paget's disease (two), microcystic adnexal cell carcinomas (two), dermatofibrosarcoma protuberans (two), and primary cutaneous neuroendocrine carcinoma (Merkel cell carcinoma) (one). The use of horizontal paraffin-embedded sections lengthens the duration of the procedure but facilitates accurate assessment of histological sections in selected tumours.

Lymphoepithelioma-like carcinoma of the skin treated with Mohs micrographic surgery in combination with immune staining for cytokeratins

Lymphoepithelioma-like carcinoma of the skin (LLCS) is a rare cutaneous neoplasm that histologically resembles nasopharyngeal lymphoepithelioma. Conventional surgical excision carries a considerable rate of recurrence (three of 11 reported cases with such treatment, with one patient dying of metastatic disease). We report the first case of lymphoepithelioma-like carcinoma of the skin treated with Mohs micrographic surgery. Because of its tendency to occur on the face and its potential for recurrence after incomplete removal, this tumor is a good candidate for treatment with Mohs micrographic surgery. Immunohistochemical staining of frozen sections for cytokeratins may help to detect neoplastic cells that may be obscured by the dense lymphoplasmacytic infiltrate associated with this tumor.

Verrucous carcinoma of the skin and mucosa

The concept of verrucous carcinoma as a clinicopathologic variant of squamous cell carcinoma is worthy of recognition. It is known by a confusing array of names, such as Ackerman's tumor, Buschke-Loewenstein tumor, florid oral papillomatosis, epithelioma cuniculatum, carcinoma cuniculatum, and cutis papillomatosis carcinoides of Gottron. Its apparent clinical benignity may lead to lengthy periods of misdiagnosis, during which it is likely not to spread to distant lymph nodes, but rather to destroy a nose, mandible, or penis as it slowly but relentlessly extends into underlying tissue. Morphologically warty or verrucous, its relatively bland histologic features are often more suggestive of a verruca vulgaris or pseudoepitheliomatous hyperplasia than of squamous cell carcinoma to those unfamiliar with the diagnosis. Alternatively, when it extends into underlying tissues, it may be mistaken histologically for a benign adnexal tumor or even an epidermoid cyst. Therapy may also be challenging because recurrences are common and concerns about potential anaplastic transformation after radiotherapy are often expressed.

Immunohistochemical techniques in Mohs micrographic surgery: their potential use in the detection of neoplastic cells masked by inflammation

BACKGROUND

Histopathologic evaluation of tissue obtained from Mohs micrographic surgery is the key step in obtaining complete tumor removal. Residual undetected tumor may result in recurrence.

OBJECTIVE

In circumstances in which the histopathologic interpretation is difficult, we assessed the potential use of immunohistochemical techniques to detect tumor in Mohs micrographic surgical specimens.

METHODS

A rapid immunoperoxidase technique with monoclonal anticytokeratin antibodies was performed on Mohs frozen sections. Cases selected included morpheaform basal cell carcinomas, perineural tumors, and sections with dense inflammation without apparent tumor.

RESULTS

Four cases are described as examples that highlight the potential usefulness of immunostaining of Mohs tissue sections. Anticytokeratin antibodies helped to confirm free tumor margins, thus avoiding the unnecessary sacrifice of normal tissue, and to delineate tumor not identified in hematoxylin and eosin frozen sections.

CONCLUSION

Immunohistochemical staining of Mohs micrographic surgical specimens with anticytokeratin antibodies is particularly useful when dense inflammatory infiltrate is present, because the latter may obscure any residual tumor. Application of this technique to difficult cases may prevent tumor recurrences or unnecessary excision of normal tissue.