Merkel cell carcinoma (MCC) is a rare neoplasm that arises in the skin of elderly patients on sun‐exposed areas such as the head, neck, and extremities. Involvement of the epidermis by tumor cells is a relatively uncommon phenomenon. However, a few cases have been reported of Merkel cell carcinoma in situ (MCCIS) in which tumor cells are confined exclusively to the epidermis without dermal involvement. Herein, we present a peculiar MCCIS lesion in a 66‐year‐old man composed of tumor cells in a nested and lentiginous growth pattern, exhibiting variable quantities of intracytoplasmic dusty brown pigment consistent with melanin, thus closely mimicking melanoma in situ. In addition, the lesion was associated with invasive squamous cell carcinoma, which has not been previously reported in the literature. An extensive search of the PubMed‐indexed, English‐language literature yielded only 17 case reports of MCCIS without documented invasion in which clinical data were available. Out of the cases with available clinical information, individuals with strict MCCIS (n = 13) showed no evidence of recurrence or metastases. The median follow‐up time in the cases with available data (n = 9) was 12 months (mean 12.8 months, range 6–21). Thus, MCCIS without invasion may have a favorable clinical course in contrast to invasive MCC tumors.

Patients can be seen where "fungal debris," "mycetoma," or "mass-like obstruction" of the sinonasal tract is suspected clinically but lack fungus and instead have granular, eosinophilic debris and bacterial colonies. We report and characterize 15 such cases, tentatively termed "bacteromas," compared with randomly selected cases of mycetoma and allergic fungal sinusitis (AFS). Pathology reports from 2016 to 2021 were searched. All candidate cases were examined microscopically and included if they had granular, amorphous debris with negative Grocott methenamine silver staining and lacked diagnostic features of other entities. The 7 males and 8 females ranged from 21 to 78 years old. Imaging frequently revealed opacification of the paranasal sinuses. Operative reports showed all to have paranasal sinus involvement. Most were unilateral (13/15, 87%). The maxillary sinus was involved in 11/15 (73%) cases, sphenoid sinus in 2/15 (13%), and frontal and ethmoid sinuses in 1/15 (7%), each. Bacteroma patients frequently had a history of allergic rhinitis (8/15, 53%), more than mycetomas (1/15, 7%) and AFS (5/15, 33%) (P = 0.0142). Facial pain was a common presenting symptom (13/15, 87%) in bacteromas compared with mycetomas (5/15, 33%) or AFS (1/15, 7%). Morphologically, cases consisted of large aggregates of paucicellular to acellular debris with a characteristic densely eosinophilic granular appearance, commonly associated with bacteria. Four of the 10 cultured patients grew Pseudomonas aeruginosa. Course posttreatment ranged from symptom resolution 1 week postoperatively to recurrent infections and symptoms 23 months from the initial operation. In summary, "bacteroma" is a heretofore undescribed pathologic entity of the sinuses that appears to be related to chronic bacterial infection and is distinct from mycetoma, AFS, and rhinolithiasis.

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Drosophila melanogaster produces fatty acid amides, and thus, provides a model to unravel the pathways for their biosynthesis. We previously demonstrated that arylalkylamine N-acetyltransferase-like 2 (AANATL2) from D. melanogaster will catalyze the formation of long-chain N-acylserotonins and N-acyldopamines in vitro. Generating silencing RNA via the UAS/GAL4 bipartite approach for targeted gene expression effectively decreased the endogenous levels of the AANATL2 transcripts in D. melanogaster, as shown by reverse transcription quantitative polymerase chain reaction. Consistent with these data, western blot analysis of the offspring of the AANATL2 knockdown flies using an anti-AANATL2 antibody revealed a significant reduction in the expression of the AANATL2 protein. Reduced expression of AANATL2 decreased the cellular levels of N-palmitoyldopamine (PALDA), providing strong evidence that AANATL2 is responsible for the biosynthesis of PALDA in vivo. This is the first time that the expression of an AANAT has been reduced in D. melanogaster to link one of these enzymes to the in vivo production of an N-acylarylalkylamide.

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