Rare association of cystic squamous cell carcinoma and small lymphocytic B cell lymphoma: successful surgical approach.

Non-melanoma skin cancer is the most common type of cutaneous neoplasm worldwide. While basal cell carcinoma is the most common tumor, squamous cell carcinoma (SCC) causes higher morbidity and has a risk of metastatic spread, depending on immune status, tumor size, and desmoplastic growth. We reported the case of a 77 year old male patient with retroauricular tumor, which started growing 3 years ago and was excised, buth relapsed three times. The initial diagnosis was infundibular cyst. Delayed Mohs surgery was performed, as was an additional open lymph node biopsy of the patient's right groin, on the occasion of an indolent swelling of the same which developed within 3 months. The first histopathological report confirmed the diagnosis of a cystic squamous cell carcinoma. The histopathologic evaluation of the groin tumor revealed a small lymphocytic B cell lymphoma (BCL). The patient fulfilled the following criteria for high-risk SCC: tumor size ≥2 cm (or 1 cm on the head and 6 mm on the genitals, hands, and feet), tumor thickness ≥4 mm, recurrent tumor, rapid growth. Therefore, lymph node metastasis had to be considered. High-risk SCC has a propensity to metastasize. In cases of primary tumor, Mohs surgery is the most effective treatment, particularly in relapsing tumors. The combination of cystic SCC with a small-sized BCL is very rare. The differential diagnosis and treatment may be challenging. In high-risk SCC, lymph node enlargement warrants histologic evaluation. However, not all suspicious lymph node lesions corroborate as metastatic.