All of the following histopathological changes are seen in psoriasis except?
**Core Concept**
Psoriasis is a chronic autoimmune skin condition characterized by abnormal keratinocyte proliferation and differentiation, leading to distinct histopathological changes. The characteristic histopathological features of psoriasis include thickening of the epidermis, increased keratinocyte turnover, and abnormal keratinization.
**Why the Correct Answer is Right**
Dyskeratosis, which refers to the premature keratinization of cells, is not typically seen in psoriasis. Instead, psoriasis is characterized by parakeratosis, a process where cells are retained in the upper epidermis due to premature keratinization. Parakeratosis is a hallmark of psoriasis, resulting from the accelerated turnover of keratinocytes. In contrast, dyskeratosis is more commonly associated with conditions such as Bowen's disease or other neoplastic processes. The thickening of the epidermis in psoriasis, known as acanthosis, is also a characteristic feature. Furthermore, hyperkeratosis, or thickening of the stratum corneum, is another common finding in psoriasis.
**Why Each Wrong Option is Incorrect**
**Option A:** Hyperkeratosis is indeed seen in psoriasis, as the accelerated turnover of keratinocytes leads to an increase in the thickness of the stratum corneum.
**Option B:** Acanthosis, or thickening of the epidermis, is also a characteristic feature of psoriasis, resulting from the increased proliferation of keratinocytes.
**Option D:** Parakeratosis, not dyskeratosis, is the correct feature of psoriasis, where cells are retained in the upper epidermis due to premature keratinization.
**Clinical Pearl / High-Yield Fact**
The histopathological features of psoriasis can be remembered using the mnemonic "PARA": Parakeratosis, Acanthosis, Retention of nuclei, and Abnormal keratinization. This mnemonic can help students recall the characteristic changes seen in psoriasis.
**✓ Correct Answer: C. Dyskeratosis**