Collision of malignant neoplasms of the skin: basosquamous cell carcinoma associated with melanoma

Collision tumors are characterized by the coexistence of two cancers in the same anatomical site and its pathogenesis remains controversial. Although uncommon, the association of basal cell carcinoma and melanocytic nevus is the most common among combinations of skin tumors. Even rarer is the association of two malignant tumors. We report a case of tumor collision representing melanoma and basosquamous cell carcinoma, a combination not previously described in the literature, since there are no reported cases of melanoma with this type of basal cell carcinoma.

A Case of Basaloid Squamous Cell Carcinoma of Rectosigmoid Colon / 대한소화기학회지

Basaloid squamous cell carcinoma is a rare and aggressive variant of squamous cell carcinoma, which mostly occurs in the upper aerodigestive tracts. Basaloid squamous cell carcinoma also typically arises in the anal canal, but is extremely rare in the lower gastrointestinal tract. A 70-year-old man presented with loose stool and intermittent hematochezia 2 months ago. Colonoscopy showed an ulceroinfiltrative mass on the rectosigmoid colon from 16 cm to 18 cm above the anal verge. Conventional colonoscope could not pass through the lesion but it was possible with pediatric colonoscope. Abdominal CT scan showed 1.6 cm sized wall thickening with circumferential luminal narrowing in the rectosigmoid colon and multiple ill-defined low density masses in both lobes of the liver. Therefore, colon cancer with liver metastasis was suspected. However, basaloid cells were noted on histologic examination, and they were weakly positive for synaptophysin on immunohistochemical study. After palliative lower anterior resection, histologic examination of the resected specimen revealed basaloid differentiation with keratin pearls, and tumor cells were positively stained with high molecular weighted cytokeratin (34BE12) and CK 5/6. Thus, the patient was finally diagnosed with basaloid squamous cell carcinoma of rectosigmoid colon with distant metastases.

Tumor de colisão de pele do pescoço / Neck skin collision tumor

O tumor de colisão ou tumor misto é uma neoplasia maligna de pele, relacionada à exposição solar e com índices de incidência de até 1,5 por cento. Apresenta comportamento clínico peculiar, em relação às demais neoplasias malignas de pele e com diagnóstico histológico, caracterizado pela colisão entre um carcinoma basocelular e um carcinoma epidermóide, ou seja, duas neoplasias com histologias distintas e interface nítida entre ambas. O caso relatado foi de paciente do sexo masculino, 73 anos, com duas lesões cervicais de crescimento progressivo nos últimos meses. O tratamento realizado foi cirúrgico, com exame histológico demonstrando a presença de carcinoma de células escamosas contíguo ao carcinoma de células basais. O acometimento preferencial ocorre em homens de pele clara, na quinta ou sexta décadas de vida. Sua localização mais comum é na cabeça e pescoço, principalmente na parte central da face. O carcinoma basoescamoso é diagnóstico diferencial, definido através de critérios histológicos distintos, uma vez que ambas neoplasias apresentam comportamento clínico semelhante. Os índices de recidiva local variam de 12 por cento a 45 por cento, enquanto que é baixo na recidiva regional, de aproximadamente 7,5 por cento. Os principais fatores prognósticos são o gênero do paciente, margens cirúrgicas, infiltração perineural e status linfonodal. O tratamento de escolha é a ressecção, sendo a radioterapia indicada na sua adjuvância e lesões irressecáveis. A recidiva local é o principal fator limitante na sobrevida livre de doença que apresenta resultados pobres.

The collision or mixed tumor is a malignant neoplasm of the skin related to sun exposure and incidence rates of up to 1.5 percent. It displays a distinctive clinical behavior in relation to other malignancies of the skin and the histological diagnosis, characterized by the collision between a basal cell carcinoma and squamous cell carcinoma, i.e., two malignancies with distinct histologies and sharp interface between them. The case reported was of a male, 73-year-old patient, with two cervical lesions progressively growing in recent months. The chosen treatment was surgery. Histological examination showed the presence of squamous cell carcinoma adjacent to basal cell carcinoma. These tumors preferentially occur in light-skinned men in the fifth or sixth decades of life. Their most common location is in the head and neck, especially in the central part of the face. The differential diagnosis of basal-squamous carcinoma is defined by distinct histological criteria, since both tumors have similar clinical behavior. Local recurrence rates vary from 12 percent to 45 percent, whereas regional ones are of approximately 7.5 percent. The main prognostic factors are gender, surgical margins, perineural infiltration and lymph node status. The treatment of choice is resection, radiotherapy being indicated as adjuvant or to inoperable lesions. Local recurrence is the main limiting factor in disease-free survival, with poor results.