A Pattern-Based Approach to Dermatopathology: Analyzing Cases from Inflammatory to Neoplastic

This video, “Dermpath Essentials Part 2,” serves as a valuable resource for dermatology residents, focusing on a systematic, pattern-based approach to interpreting skin biopsies. The session is led by Dr. Tom Davis, who uses case studies to illustrate key principles.

The presentation covers several major categories of skin conditions, providing a practical framework for diagnosis:

• Initial Analysis: The video begins by outlining the crucial first steps in analyzing a slide, such as assessing the biopsy type and anatomic location.
• Inflammatory Dermatoses: It differentiates between conditions like eczematous dermatitis and psoriasis by examining their distinct microscopic patterns.
• Neoplastic Diseases: The session highlights how to distinguish between benign and malignant tumors by looking at architectural and cytological features, using desmoplastic trichoepithelioma and microcystic adnexal carcinoma as look-alikes.
• Cysts, Deposits, and Hamartomas: Dr. Davis breaks down the classification of cysts based on their lining, discusses conditions caused by endogenous and exogenous deposits, and explains the features of common hamartomas like epidermal nevus.

This video is an excellent tool for reinforcing fundamental dermatopathology concepts and improving your diagnostic skills.

Chapter Breakdown:

• Chapter 1: Introduction and Approach to Dermatopathology [00:14]
  • This chapter introduces the video as a continuation of a dermatopathology basics series. It offers advice for junior residents on how to approach the subject, emphasizing the importance of patience, independent study, and understanding the “lives of lesions” as they evolve.
• Chapter 2: Initial Histologic Diagnosis Steps [03:46]
  • The speaker outlines a systematic approach to analyzing a biopsy slide, starting with a low-power view to count pieces and identify the biopsy type. It also stresses the importance of noting the anatomic location and the patient’s approximate age.
• Chapter 3: Categorizing Skin Conditions [07:31]
  • This section explains how to place a skin condition into one of five main “boxes”: inflammatory, neoplastic, cyst, deposit, or hamartoma/malformation.
• Chapter 4: Inflammatory Dermatoses [08:32]
  • This chapter provides two case examples: one for subacute eczematous dermatitis (like nummular eczema) and another for psoriasis. The speaker highlights the key histologic features that differentiate these two conditions, such as the pattern of epidermal hyperplasia and the nature of the scale and infiltrate.
• Chapter 5: Neoplastic Skin Diseases [17:34]
  • This section focuses on neoplastic conditions, first discussing how to differentiate benign from malignant tumors using architectural and cytological features. It then presents two case studies that are “look-alikes”: desmoplastic trichoepithelioma (benign) and microcystic adnexal carcinoma (malignant).
• Chapter 6: Cysts [27:19]
  • The video breaks down the classification of cysts based on their epithelial lining. Case examples include the common epidermal inclusion cyst (infundibular type), the pilar cyst (isthmus-catagen type), and pilomatricoma.
• Chapter 7: Deposits [33:33]
  • This chapter covers skin conditions caused by the deposition of material, which can be either exogenous (from outside the body) or endogenous (from within). The examples provided are Restylane (hyaluronic acid filler) and a gouty tophus.
• Chapter 8: Hamartomas or Malformations [37:23]
  • The speaker defines a hamartoma and provides two examples: an epidermal nevus and a nevus sebaceous, explaining their characteristic features and how they can be differentiated from other conditions.
• Chapter 9: Conclusion and Contact Information [41:14]
  • The video concludes with a summary of the concepts discussed and provides contact information for further questions.