Inflammatory Dermatopathology: Spongiotic, Psoriasiform & Interface Patterns

This video provides an excellent, in-depth guide to diagnosing inflammatory skin conditions in dermatopathology. Led by Dr. Emily DeSantis, the session is structured to help residents and pathologists develop a systematic approach to slide evaluation.

The key topics covered include:

• Systematic Evaluation: A top-down method for analyzing biopsies, starting from low power and moving from the epidermis to the dermis.
• Spongiotic Dermatitis: An overview of this pattern (eczema), with examples of acute and chronic forms, including how to differentiate between conditions like contact dermatitis and tinea infections.
• Psoriasiform Dermatitis: A discussion of this pattern, using psoriasis as the prototype and providing a broad differential diagnosis that includes psoriasiform drug reactions and mycosis fungoides.
• Interface Dermatitis: An analysis of conditions where inflammation is centered at the dermal-epidermal junction. The video explores both vacuolar (Erythema Multiforme, Fixed Drug Eruption) and lichenoid (Lichen Planus, Lupus Erythematosus) patterns.

This presentation is a valuable resource for honing diagnostic skills by focusing on the patterns and key features of common inflammatory dermatoses.

Chapter Breakdown:

• Chapter 1: Introduction and Goals [00:12]
  • The video introduces the topic of inflammatory skin lesions in dermatopathology. The speaker outlines the goals of the presentation: to provide a systematic approach to slide evaluation and an overview of common inflammatory patterns.
• Chapter 2: Importance of Communication and Biopsy Technique [01:23]
  • This section emphasizes the crucial role of communication between clinicians and pathologists. Key factors for an accurate diagnosis include a detailed clinical history, biopsy technique (preferring punch over shave), and the clinical differential diagnosis.
• Chapter 3: Systematic Approach to Biopsy Evaluation [03:39]
  • Dr. Emily Danis outlines her systematic method for evaluating biopsies, which involves starting at low power and working from the top down (stratum corneum, epidermis, dermis).
• Chapter 4: Commonly Used Terms in Inflammatory Dermatoses [05:49]
  • The video defines essential terms used in inflammatory dermatopathology, such as acanthosis, psoriasiform hyperplasia, orthokeratosis, parakeratosis, and dyskeratosis.
• Chapter 5: Categories of Inflammatory Dermatoses & Focus on Spongiotic Dermatitis [07:06]
  • This chapter introduces the main categories of inflammatory skin conditions and focuses on spongiotic dermatitis. It explains the concept of spongiosis and its clinical presentation in acute and chronic forms.
• Chapter 6: Differential Diagnosis and Examples of Acute Spongiotic Dermatitis [11:22]
  • The speaker discusses the differential diagnosis for acute spongiotic dermatitis, using a case of dyshidrotic eczema and another of tinea infection to illustrate how clinical and special stains are used to arrive at a final diagnosis.
• Chapter 7: Spongiotic Dermatitis with Intraepidermal Eosinophils (Eosinophilic Spongiosis) [15:01]
  • This section covers a specific subtype of spongiosis characterized by eosinophils. It provides a differential diagnosis that includes arthropod reactions, drug reactions, and bullous pemphigoid, and presents a case of a drug reaction.
• Chapter 8: Subacute and Chronic Spongiotic Dermatitis [17:55]
  • The video delves into the features of subacute and chronic spongiotic dermatitis, with a case of prurigo nodularis demonstrating the effects of chronic rubbing.
• Chapter 9: Psoriasiform Dermatitis [21:31]
  • This chapter introduces psoriasiform dermatitis and uses psoriasis as the prototype, explaining its classic histologic features like regular epidermal hyperplasia and suprapapillary plate thinning.
• Chapter 10: Differential Diagnosis of Psoriasiform Dermatitis [23:41]
  • The speaker provides a comprehensive differential for psoriasiform dermatitis, including chronic spongiotic dermatitis, pityriasis rubra pilaris, psoriasiform drug reactions, and nutritional deficiencies. It uses case examples to highlight the distinguishing features of each.
• Chapter 11: Interface Dermatitis – Introduction and Vacuolar Change [30:23]
  • This section introduces interface dermatitis, which is centered at the dermal-epidermal junction. It defines the two main subtypes, vacuolar and lichenoid, and uses erythema multiforme as an example.
• Chapter 12: Examples of Vacuolar Interface Dermatitis (Erythema Multiforme & Fixed Drug Eruption) [32:19]
  • The video uses cases of erythema multiforme and fixed drug eruption to demonstrate the histologic features of vacuolar interface dermatitis, emphasizing the presence of individual apoptotic cells and pigment incontinence.
• Chapter 13: Interface Dermatitis – Lupus Erythematosus [39:03]
  • This chapter focuses on Lupus Erythematosus (LE), detailing the general histologic features and highlighting specific findings for Discoid LE, such as follicular plugging and a thickened basement membrane.
• Chapter 14: Interface Dermatitis – Lichenoid Pattern (Lichen Planus and Differentials) [43:17]
  • The video uses Lichen Planus as the prototype for lichenoid dermatitis, explaining its characteristic band-like infiltrate and sawtooth rete ridges. It also discusses look-alikes like lichenoid drug reactions and lichenoid keratosis.
• Chapter 15: Conclusion and Future Topics [49:50]
  • The speaker concludes the discussion and gives a preview of upcoming topics, including pustular, granulomatous, and vesicular bullous dermatitis.