Estimated Effect of COVID-19 Lockdown on Skin Tumor Size and Survival: An Exponential Growth Model

Background and objectives

Spain is in a situation of indefinite lockdown due to the ongoing coronavirus disease 2019 (COVID-19) pandemic. One of the consequences of this lockdown is delays in medical and surgical procedures for common diseases. The aim of this study was to model the impact on survival of tumor growth caused by such delays in patients with squamous cell carcinoma (SCC) and melanoma.

Material and methods

Multicenter, retrospective, observational cohort study. We constructed an exponential growth model for both SCC and melanoma to estimate tumor growth between patient-reported onset and surgical excision at different time points.

Results

Data from 200 patients with SCC of the head and neck and 1000 patients with cutaneous melanoma were included. An exponential growth curve was calculated for each tumor type and we estimated tumor size after 1, 2, and 3 months of potential surgical delay. The proportion of patients with T3 SCC (diameter > 4 cm or thickness > 6 mm) increased from 41.5% (83 patients) in the initial study group to an estimated 58.5%, 70.5%, and 72% after 1, 2, and 3 months of delay. Disease-specific survival at 2, 5, and 10 years in patients whose surgery was delayed by 3 months decreased by 6.2%, 8.2%, and 5.2%, respectively. The proportion of patients with ultrathick melanoma (> 6 mm) increased from 6.9% in the initial study group to 21.9%, 30.2%, and 30.2% at 1, 2, and 3 months. Five- and 10-year disease-specific survival both decreased by 14.4% in patients treated after a potential delay of 3 months.

Conclusions

In the absence of adequate diagnosis and treatment of SCC and melanoma in the current lockdown situation in Spain, we can expect to see to a considerable increase in large and thick SCCs and melanomas. Efforts must be taken to encourage self-examination and facilitate access to dermatologists in order to prevent further delays.

Knowledge based recursive non-linear partial least squares (RNPLS)

Soft sensors driven by data are very common in industrial plants to perform indirect measurements of difficult to measure critical variables by using other variables that are relatively easier to obtain. The use of soft sensors implies some challenges, such as the colinearity of the predictor variables, the time-varying and possible non-linear nature of the industrial process. To deal with the first challenge, the partial least square (PLS) regression has been employed in many applications to model the linear relations between process variables, with noisy and highly correlated data. However, the PLS model needs to deal with the other two issues: the non-linear and time-varying characteristics of the processes. In this work, a new knowledge-based methodology for a recursive non-linear PLS algorithm (RNPLS) is systematized to deal with these issues. Here, the non-linear PLS algorithm is set up by carrying out the PLS regression over the augmented input matrix, which includes knowledge based non-linear transformations of some of the variables. This transformation depends on the system's nature, and takes into account the available knowledge about the process, which is provided by expert knowledge or emulated using software tools. Then, the recursive exponential weighted PLS is used to modify and adapt the model according to the process changes. This RNPLS algorithm has been tested using two case studies according to the available knowledge, a real industrial evaporation station of the sugar industry, where the expert knowledge about the process permits the formulation of the relationships, and a simulated wastewater treatment plant, where the necessary knowledge about the process is obtained by a software tool. The results show that the methodology involving knowledge regarding the process is able to adjust the process changes, providing highly accurate predictions.

Phototoxic reaction to a combined oral contraceptive (levonorgestrel/ethinylestradiol)

We present the case of a phototoxic skin reaction due to the regular intake of a combined oral contraceptive (levonorgestrel/ethinylestradiol). Upon spectrophotometer testing, we demonstrated high absorption in the UV-B region of the solar spectrum of the combined product (Ovoplex®), especially for the estrogen compound (ethinylestradiol).

A prospective study of the incidence of skin cancer and its risk factors in a Spanish Mediterranean population of kidney transplant recipients

BACKGROUND

Skin cancer is the most common malignancy occurring in kidney transplant recipients (KTRs).

OBJECTIVES

Our purpose was to investigate, prospectively, the cumulative incidence of cancerous and precancerous skin lesions as well as their risk factors in a close follow-up population of KTRs from a Mediterranean area of Spain.

PATIENTS AND METHODS

One hundred and seventy-four consecutive KTRs were examined at the moment of transplant and then at 6-month intervals. The cumulative incidence of skin cancer was computed. To analyse the role of potential risk factors (age at transplantation, cause of renal failure, duration of pretransplant dialysis, type of immunosuppressive regimen, sun-reactive skin type and history of occupational sun exposure), the Cox regression method was used.

RESULTS

After a median follow-up of 72 months (range, 12-140), 39 patients (25.3%) developed 142 tumours [84 basal cell carcinoma (BCC) and 58 squamous cell carcinoma (SCC)]. The BCC/SCC ratio was 1.4 : 1. The cumulative incidence for skin cancer was 13% after 3 years of graft survival, increasing to 27.5% at 6 years and 48% at 10 years. Only age at the time of transplantation and occupational sun exposure had statistical significance as risk factors (P < 0.001).

CONCLUSIONS

Our study confirms the high incidence of non-melanoma skin cancer among KTRs in a Mediterranean population with occupational sun exposure and the patient's age at the time of transplantation being the main risk factors. We believe that all organ transplant programs should provide educational information about protecting oneself from the sun as well as include follow-up visits by dermatologists in order to facilitate early diagnosis and treatment of skin cancer.

Hereditary hypotrichosis simplex

Hypotrichosis is a relatively common feature of a number of complex hereditary syndromes. However, the isolated variant, called hereditary hypotrichosis simplex (HHS), is especially uncommon. We present a Spanish family with 8 of 19 persons covering 4 generations affected by HHS. No associated ectodermal or other defects were noted. The pedigree was compatible with an autosomal dominant inheritance with variable penetrance.

p53 immunohistochemical expression in early posttransplant-associated malignant and premalignant cutaneous lesions

BACKGROUND

Current evidence suggests that p53 accumulation is critical to the development of skin cancer in the general population. It is possible, however, that the molecular steps involved in transplant-associated and non-transplant-associated skin carcinogenesis may differ.

OBJECTIVE

Our purpose was to examine p53 expression in premalignant and malignant skin lesions from renal transplant recipients (RTRs) in their first 3 years of immunosuppression, as well as in equivalent lesions from immunocompetent normal individuals.

METHODS

p53 expression was examined by routine immunohistochemical methods using the anti-p53 monoclonal antibody DO7.

RESULTS

p53 immunoreactivity was more prevalent in dysplastic epidermal keratoses and cutaneous carcinomas from RTRs than in equivalent lesions from nontransplant controls. Statistical analysis revealed significant differences, however, only in premalignant skin lesions (p = 0.03).

CONCLUSION

This study demonstrates that accumulation of p53 protein is frequently encountered in both premalignant and malignant skin lesions of RTRs, and that this may occur as an early step in transplant-associated skin carcinogenesis.

Low-grade mucoepidermoid carcinoma on the vermilion border of the lip

We report a case of primary cutaneous carcinoma with mucoepidermoid features located on the vermilion border of the lower lip, at a distance from both salivary glands and cutaneous adnexal structures. The clinical appearance of the present case, which is similar to that of conventional cutaneous squamous cell carcinoma, as well as the existence of surrounding areas of actinic cheilitis favors the hypothesis of a phenomenon of mucinous metaplastic change in a squamous cell carcinoma. We consider that, independently of their origin, tumors having mucin-secreting and squamous differentiation ought to be named according to the same criteria generally used for other organs, namely, "low grade mucoepidermoid carcinoma" would designate tumors with bland mucin-secreting cells and well-differentiated squamous component, and "high grade mucoepidermoid carcinoma" would indicate their less well differentiated counterpart. We propose to reserve the term "adenosquamous carcinoma" for aggressive tumors with high-grade glandular and squamous elements, marked nuclear atypia, frequent mitoses, and extensive necrosis.

CD44 distribution in sweat gland tumors suggests it has different functional roles in the various cell types

CD44 is a polymorphic group of membrane glycoproteins with multiple functions that include cell adhesion. Since on normal sweat glands CD44 is expressed only in eccrine coil secretory cells, it has been considered as a possible marker of this type of differentiation. We have immunohistochemically investigated the distribution of CD44 in paraffin-embedded samples of 41 benign and malignant sweat gland tumors by using a monoclonal antibody directed against the standard isoform of CD44. CD44 was strongly expressed in epithelial cells at the peripheral row of syringomas and in cuticular areas of eccrine poromas. Apocrine tumors such as apocrine hidrocystoma, syringocystadenoma papilliferum, or hidradenoma papilliferum showed intense CD44 positivity in the portion of cells in contact with the neighboring stroma and focally on the luminal side of cells with apocrine secretion. Cylindromas and spiradenomas presented focal CD44 positivity, virtually limited to clear cells. Malignant neoplasms exhibited irregular CD44 staining, which was more intense in the less differentiated zones and tumors. Our results indicate that CD44 is not a useful marker for a specific form of sweat gland differentiation. Nevertheless, its characteristic patterns of distribution might reflect the variety of functional roles assumed by the different CD44 isoforms in each epithelial cell.

Epidermal dysplasia and neoplasia in kidney transplant recipients

BACKGROUND

Established data confirm an increased incidence of skin cancer, mainly squamous cell carcinoma (SCC), in long-term kidney transplant recipients (KTRs).

OBJECTIVE

Our purpose was to investigate prospectively the type and frequency of neoplastic and preneoplastic skin lesions in KTRs during the first 3 years of immunosuppression, as well as the influence of potential risk factors.

METHODS

Eighty-one consecutive KTRs were examined every 6 months during the first 3 years after transplantation. All survival analyses were performed with the EGRET statistical software package.

RESULTS

After a median follow-up of 34 months, 25 skin cancers developed in 12 patients; the basal cell carcinoma (BCC)/SCC ratio was 3.1:1. The cumulative risk of skin cancer developing after 3 years of graft survival was 18.1%. Only age at the time of transplantation (p = 0.005) and occupational sun exposure (p = 0.048) had statistical significance as risk factors.

CONCLUSION

In carefully supervised KTRs, a high incidence of cutaneous malignancy, mainly BCC, exists in the early posttransplant period. Sun exposure and the patient's age at the time of transplantation seem to be the most important risk factors.

[Cholesterol embolism]

Two patients with advanced atherosclerotic vascular disease developed multiple cholesterol emboli. In both patients the clinical presentation included livedo reticularis of the lower part of the body and purple toes with small areas of distal necrosis and ulceration. The predisposing factors are operative vascular procedures and the use of anticoagulants respectively. Biopsy of skin lesions revealed characteristic cholesterol clefts within atheromatous debris filling small, deep arterial lumen. Multiple cholesterol emboli should be suspected in presence of cutaneous lesions and confirmed histologically in the appropriate clinical setting.