A 1-min double embedding method for small tissue specimens preserves comedone histology and eliminates the need for punch biopsies.

Background: It is difficult to preserve the structure and microbial distribution inside comedonal plugs during routine processing.

Objective: The objective of this study is to determine the optimal method to preserve the comedonal corneum plug structure and inherent microorganisms thereby eliminating the need to perform punch biopsies in relevant studies.

Methods: Corneum plugs were extracted from comedones of acne vulgaris patients. Primary embedding using either a 2% agarose, 2% agar, 25% gelatin, or 2% agar + 2.5% gelatin solution was subsequently performed and the results compared. The specimens were then fixed, waxed, sectioned, and examined by light, fluorescence, and scanning electron microscopies to observe the structures and microorganisms within the plugs.

Results: Both the 25% gelatin and 2% agarose solutions successfully preserved the structural integrity of corneum plugs and the inherent microorganisms. When considering other factors such as thermostability, reusability, and convenience, the 25% gelatin solution was the superior choice among the four materials.

Conclusion: We report a simple and effective method for double embedding comedonal plugs and other small tissue specimens. The technique preserves the structure and microbial distribution in situ within comedonal corneum plugs, eliminates the need for punch biopsies. This method may also be applied to other tiny and fragile tissue specimens, thereby enabling a potentially wide array of future large-scale investigations and alleviated patients' pain.