Melanoma of Unknown Primary Presenting as a Single Back Mass

In this report, we present a case involving the discovery of metastatic melanoma within a mid-right back mass with the clinical presentation of an epidermoid cyst, but the histological qualities of a lymph node. A 43-year-old male presented with a 5 cm x 5 cm cyst-like mass on his mid-right back that had become painful over the last year and consequently underwent three surgical procedures. First, initial excision of the back mass and histological examination resulted in a diagnosis of metastatic melanoma without epidermal involvement. This was followed by re-excision of the back mass site and sentinel node excision, and finally, lymph node dissection of the right axilla. Of the lymph nodes examined, the sentinel node in the right axilla alone showed evidence of melanoma. The absence of a primary lesion or any histological evidence of regression in a presumed primary site resulted in a diagnosis of melanoma of unknown primary, or occult primary melanoma. To our knowledge, this is the first documented case of an occult primary melanoma presenting as a single mass representing a lymph node in the back

BECLIN1 is essential for intestinal homeostasis involving autophagy-independent mechanisms through its function in endocytic trafficking

Abstract Autophagy-related genes have been closely associated with intestinal homeostasis. BECLIN1 is a component of Class III phosphatidylinositol 3-kinase complexes that orchestrate autophagy initiation and endocytic trafficking. Here we show intestinal epithelium-specific BECLIN1 deletion in adult mice leads to rapid fatal enteritis with compromised gut barrier integrity, highlighting its intrinsic critical role in gut maintenance. BECLIN1-deficient intestinal epithelial cells exhibit extensive apoptosis, impaired autophagy, and stressed endoplasmic reticulum and mitochondria. Remaining absorptive enterocytes and secretory cells display morphological abnormalities. Deletion of the autophagy regulator, ATG7, fails to elicit similar effects, suggesting additional novel autophagy-independent functions of BECLIN1 distinct from ATG7. Indeed, organoids derived from BECLIN1 KO mice show E-CADHERIN mislocalisation associated with abnormalities in the endocytic trafficking pathway. This provides a mechanism linking endocytic trafficking mediated by BECLIN1 and loss of intestinal barrier integrity. Our findings establish an indispensable role of BECLIN1 in maintaining mammalian intestinal homeostasis and uncover its involvement in endocytic trafficking in this process. Hence, this study has important implications for our understanding of intestinal pathophysiology