Non-Hodgkin lymphoma and skin cancer: A dangerous combination

CD73 Is an Immunometabolic Biomarker of Poor Prognosis in Patients With Primary Cutaneous Squamous Cell Carcinoma and Hematologic Malignancy

BACKGROUND

Impaired immunity may drive the increased incidence and aggression of cutaneous squamous cell carcinoma (cSCC) in patients with hematologic malignancy; however, precise mechanisms and prognostic biomarkers remain undefined. CD73 maintains elevated immunosuppressive adenosine levels and is associated with poor prognosis in several tumor microenvironments.

OBJECTIVE

Identify poor outcome biomarkers in patients with cSCC and hematologic malignancy.

MATERIALS AND METHODS

Differentially expressed genes in tumors from patients with hematologic malignancy experiencing good (n = 8) versus poor (n = 7) outcomes were identified by NanoString analysis. Results were validated at the protein level using CD73 immunohistochemistry in cSCC patients with (n = 38) and without (n = 29) hematologic malignancy.

RESULTS

Forty-eight genes were differentially expressed in tumors from patients with hematologic malignancy experiencing good versus poor outcomes. CD73 gene expression was >2-fold higher in patients with poor versus good outcomes or normal skin. Significantly increased CD73 protein levels were observed in cSCC tumors with poor versus good outcomes from patients with hematologic malignancies (p < .01), whereas no differences were noted in tumors with poor versus good outcomes from patients without hematologic malignancies (p = .49).

CONCLUSION

CD73 is highly expressed in poor prognosis cSCC from patients with hematologic malignancy and may represent a useful biomarker and potential therapeutic target.

Cutaneous malignancies in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a common lymphoid malignancy that is associated with an increased risk of developing cutaneous malignancies. Clinical outcomes for these malignancies, including melanoma and keratinocyte cancers (KC), are worse for patients with CLL. Individuals with CLL develop an immunodeficiency of both the adaptive and innate immune system, which plays a role in the increased prevalence of skin cancers. This review focuses on the complex interplay between genetics, immunity, and pathogens that influence the cellular composition and biology of skin tumors and their microenvironment in CLL patients, and in comparison with other chronic hematological malignancies. It is paramount for dermatologists to be aware of the association between CLL (and chronic hematological malignancies more broadly) and cutaneous malignancies. This is a high-risk population who require regular and vigorous dermatologic follow-up.

ABO blood group and skin cancers

Beside the role of ABO group in immunohaematology, there is accumulating evidence that the ABO blood group also plays a key role in various human disorders. The interest in blood groups and their association with disease stems from the awareness that blood group antigens are incredibly important components in the process of cell maturation and control. Studies have indicated a link between cancer and the ABO blood group. The appearance or disappearance of blood type antigens is now considered a hallmark of malignancy in many common cancers. Several tumour markers are in fact known blood group antigens. The aim of this review is to describe the history and possible functions of the ABO group and then summarize the association between blood groups and skin cancers.

Cutaneous squamous cell carcinoma in patients with chronic lymphocytic leukemia: a systematic review of the literature

The continuous improvement of life expectancy of patients with chronic lymphocytic leukemia (CLL) has resulted in increased risk of second primary malignancy that potentially may affect survival and quality of life of CLL patients. We performed a systematic review to assess the risk and the clinical‐pathological features and prognosis of cutaneous squamous cell carcinoma (cSCC) in patients with CLL. We searched PubMed, Embase, and Cochrane Central Register of Control Trials databases for articles published from database inception to December 31, 2019. English‐language studies reporting original data on patients with a specific diagnosis of CLL and cSCC were included. Data were extracted using a standardized extraction form, and any discordance was resolved by consensus. Descriptive data were generated by pooling patients from eligible studies. Of the 4588 non‐duplicate records identified, 55 articles met our inclusion criteria. These studies reported that CLL patients have a 3.2% prevalence of cSCC, with an 11.5% cSCC‐related lethality and an overall risk of metastasis of 5.7% (7.3% for regional lymph node involvement and 3.8% for distant metastasis). The quality of evidence was limited by the high heterogeneity in the design, populations, and objectives of the included studies. This systematic review suggests that cSCC in CLL patients tends to behave less aggressively compared with the solid organ transplant recipients but has a higher morbidity and mortality than in the general population. Future prospective studies are needed to increase the quality of evidence and to determine the best treatment modalities and screening intervals for these patients.

The impact of prior malignancies on the development of second malignancies and survival in follicular lymphoma: A population‐based study

We assessed the impact of a prior malignancy diagnosis (PMD) – as a potential proxy for genetic cancer susceptibility – on the development of a second primary malignancy (SPM) and mortality in follicular lymphoma (FL) patients. From the nationwide Netherlands Cancer Registry, we selected all adult FL patients diagnosed in 1994‐2012 (n = 8028) and PMDs and SPMs relative to FL, with follow‐up until 2017. We constructed two Fine and Gray models – with death as a competing risk – to assess the association between a PMD and SPM incidence. A PMD was associated with an increased incidence of SPMs (subdistribution hazard ratio [SHR], 1.30; 95% confidence interval [CI], 1.03‐1.64) – especially carcinomas of the respiratory tract (SHR, 1.83; 95% CI, 1.10‐3.05) and cutaneous squamous cell carcinomas (SHR, 1.58; 95% CI, 1.01‐2.45) – and a higher risk of mortality in a multivariable model (HR, 1.43; 95% CI, 1.19‐1.71). However, when additionally adjusted for the receipt of systemic therapy and/or radiotherapy before FL diagnosis, only patients who received such therapies had an increased incidence of SPMs (SHR, 1.40; 95% CI, 1.02‐1.93). In conclusion, patients with a PMD had a higher rate of SPMs and mortality than those without a PMD, which might have resulted from therapy‐related carcinogenesis.

Risk of cutaneous T-cell lymphoma in patients with chronic lymphocytic leukemia and other subtypes of non-Hodgkin lymphoma

BACKGROUND

Second hematologic cancers in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) are well documented and include Hodgkin lymphoma, therapy-related acute myeloid leukemia/myelodysplastic syndromes, and transformation to diffuse large B-cell lymphoma. Although cutaneous T-cell lymphoma (CTCL) has been reported in patients with CLL, the incidence and comparison to expected rates are unknown. We evaluated the incidence of CTCL among patients with CLL or other non-Hodgkin lymphoma (NHL) subtypes using data from the Surveillance, Epidemiology, and End Results (SEER) Program.

METHODS

We searched the SEER 13 registries for patients with a diagnosis of CLL and NHL between 1992 and 2008. Among patients identified, we evaluated the incidence of CTCL.

RESULTS

Among 31,286 patients with CLL, the incidence of CTCL was not significantly higher in men than women: 104.2 (95% CI, 50.0-191.8) and 28.1 (95% CI, 3.4-101.3) per 1,000,000 person-years, respectively (P = 0.06). Among 97,691 patients with NHL, the incidence of CTCL was similar in men and women (97.9 [95% CI, 62.0-146.9] and 92.0 [95% CI, 56.2-142.1] per 1,000,000 person-years, respectively; P = 0.84). The incidence of CTCL among males with CLL (standardized incidence ratio [SIR], 3.0 [95% CI, 1.4-5.5]), males with NHL (SIR, 3.7 [95% CI, 2.3-5.5]), and females with NHL (SIR, 5.9 [95% CI, 3.6-9.1]) was significantly higher than expected in the general population (all P < 0.001).

CONCLUSION

The risk of CTCL is greater in men with CLL than in the general population. In patients with NHL, both men and women are at greater risk for CTCL than in the general population.

Melanoma in patients with chronic lymphocytic leukemia and non-Hodgkin lymphoma

BACKGROUND

The relationship between melanoma and chronic lymphocytic leukemia (CLL) or non-Hodgkin lymphoma (NHL) has been minimally investigated.

OBJECTIVE

The objective of this study was to examine the incidence of melanoma in patients with a history of CLL or NHL, and their associated mortality.

METHODS

Cohorts of Kaiser Permanente Southern California members with a history of CLL and NHL were identified. Age-adjusted incidence density rates of melanoma among patients with CLL or NHL were compared with rates of melanoma among the general population of Kaiser Permanente Southern California patients. The mortality of patients with melanoma was examined using Cox proportional hazards modeling.

RESULTS

The age-adjusted incidence rate per 100,000 person-years for melanoma among patients with either CLL or NHL was 107 (95% confidence interval 84.4-129.6) versus 25.9 among the general population (95% confidence interval 84.4-129.6, P < .001). Patients with melanoma and a history of CLL or NHL had 2.46 greater odds of death compared with those without CLL or NHL (95% confidence interval 1.77-3.41).

LIMITATIONS

This study was retrospective in nature; the International Classification of Diseases, Ninth Revision codes used may contain diagnostic errors; and only overall survival was used in our analysis.

CONCLUSIONS

Patients with a history of CLL or NHL have a higher incidence of melanoma. Patients with CLL or NHL who are subsequently given the diagnosis of melanoma have a higher mortality than patients with melanoma without a preceding diagnosis of CLL.

Accuracy of sentinel lymph node dissection for melanoma staging in the presence of a collision tumour with a lymphoproliferative disease

Sentinel lymph node dissection (SLND) identifies melanoma patients with metastatic disease who would benefit from radical lymph node dissection (RLND). Rarely, patients with melanoma have an underlying lymphoproliferative disease, and melanoma metastases might develop as collision tumours in the sentinel lymph node (SLN). The aim of this study was to measure the incidence and examine the effect of collision tumours on the accuracy of SLND and on the validity of staging in this setting. Between 1998 and 2012, 750 consecutive SLNDs were performed in melanoma patients using the triple technique (lymphoscintigraphy, gamma probe and blue dye). The validity of SLND in collision tumours was analysed. False negativity was reflected by the disease-free survival. The literature was reviewed on collision tumours in melanoma. Collision tumours of melanoma and chronic lymphocytic leukaemia (CLL) were found in two SLN and in one RLND (0.4%). Subsequent RLNDs of SLND-positive cases were negative for melanoma. The patient with negative SLND developed relapse after 28 months with an inguinal lymph node metastasis of melanoma; RLND showed collision tumours. The literature review identified 12 cases of collision tumours. CLL was associated with increased melanoma incidence and reduced overall survival. This is, to our knowledge, the first assessment of the clinical value of SLND when collision tumours of melanoma and CLL are found. In this small series of three patients with both malignancies present in the same lymph node basin, lymphocytic infiltration of the CLL did not alter radioisotope uptake into the SLN. No false-negative result was observed. Our data suggest the validity of SLND in collision tumours, but given the rarity of the problem, further studies are necessary to confirm this reliability.

Melanotic and non-melanotic malignancies of the face and external ear - A review of current treatment concepts and future options

Skin has the highest incidence and variety of tumors of all organs. Its structure is of great complexity, and every component has the potential to originate a skin neoplasm (SN). Because of its exposed nature, skin is vulnerable to carcinogenic stimuli such as UV radiation. Various entities can cause SN. Nonmelanotic skin cancers (NMSC) are the most common of all cancers, with over one million cases diagnosed annually in the US. Basal cell carcinoma (BCC) accounts for approximately 80% of all NMSC, most of the remaining 20% being squamous cell carcinoma (SCC). The skin of the head and neck is the most common site for tumors, accounting for more than 80% of all NMSC. BCC, SCC, and malignant melanomas (MM) represent 85-90% of all SN. Merkel cell tumors (MCC), lymphoepithelioma-like carcinomas of the skin (LELCS), dermato-fibro-sarcomas, leiomyosarkomas, and Kaposi-sarcomas are less frequent in the facial skin region and the external ear. Based on data from the German Federal Cancer Registry (2003/2004), 140,000 people in Germany were affected by SN (100,000 BCC, 22,000 SCC, 22,000 MM). This number increases considerably if malignant precursors, such as actinic keratosis, are included. Each year, the frequency of SN diagnosis rises by 3-7%. Among all known malignant tumors, MM exhibits the highest rate of increase in incidence. In the past, SN was primarily diagnosed in people aged 50 years or older. However, recently, the risk for developing SN has shifted, and younger people are also affected. Early diagnosis is significantly correlated with prognosis. Resection of SN creates defects that must be closed with local or microvascular flaps to avoid functional disturbing scar formation and deflection of the nose, eyelids, or lips. All therapeutic strategies for SN, the current standard for adjuvant and systemic treatment, and the management of the increasing number of patients under permanent blood thinner medication are described with regard to the treatment of SN.

Relationships between skin cancers and blood groups--link between non-melanomas and ABO/Rh factors

BACKGROUND

This investigation focused on possible relationships between skin cancers and ABO/Rh blood groups.

MATERIALS AND METHODS

Between January 2005 and December 2012, medical data of 255 patients with skin cancers who were admitted to Kayseri Training and Research Hospital, Radiation Oncology and Plastic Surgery Outpatient Clinics were retrospectively analyzed. Blood groups of these patients were recorded. The control group consisted of 25701 healthy volunteers who were admitted to Kayseri Training and Research Hospital, Blood Donation Center between January 2010 and December 2011. The distribution of the blood groups of the patients with skin cancers was compared to the distribution of ABO/Rh blood groups of healthy controls. The association of the histopathological subtypes of skin cancer with the blood groups was also investigated.

RESULTS

Of the patients, 50.2% had A type, 26.3% had O type, 16.1% had B type, and 7.5% had AB blood group with a positive Rh (+) in 77.3%. Of the controls, 44.3% had A type, 31.5% had 0 type, 16.1% had B type, and 8.1% had AB blood group with a positive Rh (+) in 87.8%. There was a statistically significant difference in the distribution of blood groups and Rh factors (A Rh (-) and 0 Rh positive) between the patients and controls. A total of 36.8% and 20.4% of the patients with basal cell carcinoma (BCC) had A Rh (+) and B Rh (+), respectively, while 39.2% and 27.6% of the controls had A Rh (+) and B Rh (+), respectively. A significant relationship was observed between the patients with BCC and controls in terms of A Rh (-) (p=0.001).

CONCLUSION

Our study results demonstrated that there is a significant relationship between non-melanoma skin cancer and ABO/Rh factors.

Risk of second primary malignancies following a diagnosis of cutaneous malignant melanoma or nonmelanoma skin cancer in Alberta, Canada from 1979 to 2009

BACKGROUND

Recent studies have revealed geographical variations with respect to the risk of second primary malignancies (SPMs) following cutaneous malignant melanoma (CMM) and nonmelanoma skin cancer (NMSC).

OBJECTIVES

To provide the largest analysis of the risk of SPM following skin cancers in Canada and to detect associations that may shed light on common pathogeneses between linked malignancies.

METHODS

Relative risks for development of SPMs following a diagnosis of CMM or NMSC were calculated via a retrospective analysis of data retrieved from the Alberta Cancer Registry (ACR) from 1979 to 2009.

RESULTS

From 1979 to 2009, 85,967 NMSC and 6884 CMM incident cases were recorded in the ACR. In total 19,869 SPMs were identified following a primary NMSC (7709 cutaneous and 12,160 noncutaneous), while 1437 SPMs (908 cutaneous and 529 noncutaneous) followed CMM. Patients with a previous history of skin cancer had a 60% increased risk of developing an SPM compared with those without [observed/expected ratio (O/E) 1.6, 95% confidence interval (CI) 1.6-1.7; P < 0.001]. Thirty and 10 different SPMs were significantly identified to follow a diagnosis of NMSC and CMM, respectively. Patients under the age of 40 years with a prior history of CMM had a marked increased expectancy for SPM [O/E 5.6, 95% CI 4.5-7.0; P < 0.001).

CONCLUSIONS

Further studies are warranted to identify environmental and molecular connections among linked cutaneous and noncutaneous malignancies, which may lead to earlier detection of related neoplasms via expanded screening protocols and development of shared treatment regimens. Heightened surveillance for the development of SPMs in patients with CMM under the age of 40 years should be considered.

Cutaneous T-cell lymphoma in patients with chronic lymphocytic leukemia: clinical characteristics, temporal relationships, and survival data in a series of 14 patients at Mayo Clinic

BACKGROUND

We examined the course of cutaneous T-cell lymphoma (CTCL), which has been associated with chronic lymphocytic leukemia (CLL) in patients with CLL.

MATERIALS AND METHODS

A search was conducted of the master diagnosis index at our institution to identify patients with both CLL and CTCL from 1980 to 2010. A retrospective chart review was then conducted.

RESULTS

Of the 14 patients with CTCL and CLL, eight had mycosis fungoides (MF; two with patch stage, two with plaque stage, two with tumor stage, and two with erythrodermic stage), four had Sézary syndrome, one had natural killer cell lymphoma involving the skin, and one had peripheral T-cell lymphoma involving the skin. Eight had concurrent diagnoses, five received a CLL diagnosis first, and one received a CTCL diagnosis first. Ten patients were deceased at the time of data abstraction due to unknown causes (n = 4), lymphoma (n = 2), pneumonia (n = 2), MF (n = 1), or respiratory failure (n = 1). Of the nine patients with concurrent or prior CTCL, seven were deceased, with a median time to death of 10.2 months (range, 6-89 months). Of the five patients with CLL prior to CTCL, three were deceased at 18, 27, and 47 months, respectively, after the CTCL diagnosis. The median survival for the two groups was 12 and 47 months, respectively.

CONCLUSIONS

Patients with CTCL concurrent with or prior to CLL have a worse overall survival than patients with CLL in whom CTCL later develops. Larger studies are needed.

Melanoma and rituximab: an incidental association?

Rituximab is an anti-CD20 monoclonal antibody increasingly used in haematology and rheumatology, but also in internal medicine and dermatology. It has a good tolerance profile without known increased risk of cancer. We report a case of nodular melanoma with a 4.8 mm Breslow thickness that appeared after 2 years of rituximab in a 45-year-old patient with non-Hodgkin lymphoma. Fifteen additional rituximab-associated melanoma cases in 13 patients have been identified in the literature and in the EudraVigilance database. These patients were treated for various indications and had melanomas, often aggressive, initially diagnosed at a metastatic stage in 31% of cases. Our work raises the question of rituximab accountability in melanoma onset in these immunosuppressed patients. A dermatological monitoring seems necessary in patients treated with rituximab, especially in case of risk factors for melanoma. In case of individual melanoma history, the benefit/risk ratio of initiating rituximab therapy should be carefully assessed.

Melanoma in immunosuppressed patients

The immunogenic characteristics of malignant melanoma are intriguing. To date, multiple studies exist regarding the immunogenicity of melanoma. In this article, we summarize data in the literature on the role of immunosuppression in melanoma and discuss several immunocompromised patient populations in detail. A comprehensive PubMed search was conducted with no date limitation. The following search terms were used: melanoma in combination with immunosuppression, immunocompromised, genetics, antigen processing, UV radiation, organ transplantation, organ transplant recipients, lymphoproliferative disease, lymphoma, CLL, NHL, radiation, and HIV/AIDS. Although no formal criteria were used for inclusion of studies, most pertinent studies on the topic were reviewed, with the exception of smaller case reports and case series. The included studies were generally large (≥ 1000 patients in organ transplant recipient studies; ≥ 500 patients in lymphoma studies), with a focus on institutional experiences, or population-based national or international epidemiologic studies. Melanoma-induced immunosuppression, the role of UV radiation in melanoma development, and the epidemiology, clinical course, and prognosis of melanoma in immunocompromised patients are highlighted. Organ transplant recipients, patients with lymphoproliferative disorders, patients with iatrogenic immunosuppression, and patients with human immunodeficiency virus infection/AIDS are also highlighted. Recommendations are proposed for the care and monitoring of immunosuppressed patients with melanoma. With better understanding of the molecular microenvironment and clinical course of melanoma in immunosuppressed patients, novel therapies could be developed and outcomes potentially affected in these patients.

Chronic lymphocytic leukemia is associated with decreased survival of patients with malignant melanoma and Merkel cell carcinoma in a SEER population-based study

PURPOSE

To delineate outcomes of malignant melanoma (MM) and Merkel cell carcinoma (MCC) in patients with chronic lymphocytic leukemia (CLL) or non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

We identified patients with MM or MCC reported to the Surveillance, Epidemiology, and End Results program and analyzed the effects of history of CLL/NHL on overall (OS) and cause-specific survival after MM or MCC. Expected survival was derived from patients with MM or MCC without CLL/NHL.

RESULTS

From 1990 to 2006, 212,245 patients with MM and 3,613 patients with MCC were identified, of whom 1,246 with MM and 90 with MCC had a prior diagnosis of CLL/NHL. Patients with MM and a history of CLL/NHL had worse-than-expected OS as measured by standardized mortality ratio (SMR; SMR for CLL, 2.6; 95% CI, 2.3 to 3.0; SMR for NHL, 2.3; 95% CI, 2.1 to 2.6). MM cause-specific survival was worse than expected for patients with a history of CLL (SMR, 2.8; 95% CI, 2.2 to 3.4) or NHL (SMR, 2.1; 95% CI, 1.7 to 2.6). Among patients with MCC, OS was worse than expected for those with a history of CLL (SMR, 3.1; 95% CI, 2.2 to 4.3) or NHL (SMR, 1.9; 95% CI, 1.3 to 2.8). MCC cause-specific survival was worse than expected for patients with a history of CLL (SMR, 3.8; 95% CI, 2.5 to 5.9), but no difference was observed for NHL (SMR, 0.9; 95% CI, 0.4 to 2.1).

CONCLUSION

Patients with CLL before diagnosis of MM or MCC have significantly worse OS and MM or MCC cause-specific survival than those without a history of CLL/NHL.

Merkel cell carcinoma metastatic to the transverse colon: disease free after six years - cure or just prolonged remission?

Merkel cell carcinoma is an uncommon but highly immunogenic skin malignancy that has the potential to metastasize to any site in the body. Despite treatment many patients experience relapse, often to distant sites beyond the site of initial treatment. The development of distant soft tissue or visceral metastases is considered incurable, despite treatment with prognosis usually being measured in months. We report the case of an elderly man who developed colonic metastases from a head and neck primary and with treatment has survived disease free for over 6 years. Such reports are infrequently documented and highlight the unpredictable nature of this disease.

Non-melanoma skin cancer

The rising incidence and morbidity of non-melanoma skin cancers has generated great interest in unravelling of their pathogenesis and in the search for new non-invasive treatments. Whereas the role of cumulative sun exposure in pathogenesis of squamous-cell carcinoma seems clear, the relation between sun-exposure patterns and subtypes of basal-cell carcinoma remains undetermined. Several complex genotypic, phenotypic, and environmental factors contribute to pathogenesis of non-melanoma skin cancers. Unlike basal-cell carcinoma, squamous-cell carcinomas can arise from precursor lesions. Diagnosis of non-melanoma skin cancer is made clinically and confirmed by histological testing. Prognosis depends on lesion and host characteristics, which also dictate choice of treatment. Prevention strategies aim at reduction of sun exposure, but are of unproven benefit, especially for basal-cell carcinoma. Surgical excision with predetermined margins is the mainstay of treatment for squamous-cell carcinoma and for most basal-cell carcinomas. Of the new non-invasive treatments, only photodynamic therapy and topical imiquimod have become established treatments for specific subtypes of basal-cell carcinoma, and the search for more effective and tissue-salvaging therapies continues.

The important role of radiotherapy in patients with non-melanoma skin cancer and other cutaneous entities

Non-melanoma skin cancer is the commonest malignancy worldwide and a significant public health issue. Although most non-melanoma skin cancers are small and easily excised or ablated, a recommendation of definitive radiotherapy is often made in patients where the outcome (cosmetic and/or functional) will probably be better with radiotherapy compared to surgery. The aim of adjuvant radiotherapy is to reduce the risk of loco-regional recurrence and the role of palliative radiotherapy is important in improving the quality of life in patients with advanced and/or incurable disease. The aim of this review article is to broadly discuss the various clinical settings in which a recommendation of radiotherapy may be made and also includes a discussion on less frequently encountered cutaneous entities (e.g. in situ squamous cell carcinoma, keratocanthoma, lentigo maligna, cutaneous lymphomas and malignant fibrous tumours).

Progressive trichodysplasia spinulosa in a patient with chronic lymphocytic leukaemia in remission

A 70-year old Caucasian man with chronic lymphocytic leukaemia developed trichodysplasia spinulosa 2 months after ceasing chemotherapy. Histological features characteristic to this condition include dilated and enlarged hair follicles, hyperplastic hair bulbs, hyperplasia of inner root sheath cells with numerous large, eosinophilic, trichohyaline granules, and hypercornification. Although he was in remission for chronic lymphocytic leukaemia, lesions were slowly progressive 15 months after cessation of chemotherapy. We also describe a painless pull-test where spicules can be easily plucked and assessed microscopically for inner root sheath keratinization, or observed with surface microscopy in a clinic setting.