DERMATOPATHOLOGY CASES: Self-Assessment Cases: Editor - Dr Sampurna Roy MD

Digital Images of interesting cases that will include the full spectrum of Dermatopathology, presented in the form of quiz.

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Sunday, December 6, 2009

Answer of Dermatopathology Case 3

Large Cell Acanthoma

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A conjunctival lesion with histological features similar to large-cell acanthoma of the skin.J Cutan Pathol. 2009 Aug 27.
Large-cell acanthoma (LCA) is a sharply demarcated epidermal lesion composed oflarge keratinocytes and characterized by hyperkeratosis, hypergranulosis and orthokeratosis. It usually affects actinically damaged skin. LCA is currentlybelieved to be a distinct entity with an unclear pathogenesis and a benign biologic behavior. Here, we describe the first occurrence of LCA in theconjunctiva. The lesion recurred following initial excision, and later recurred as a carcinoma in situ following a second excision. This case suggests that LCA may have a malignant and transformation potential. Ghazi NG, Patel BS, OlsakovskyLeslie A, White K, Patterson JW. A conjunctival lesion with histological features similar to large-cell acanthoma of the skin.

Large cell acanthoma.Int J Dermatol. 2003 Jan;42(1):36-9.
The large cell acanthoma presents as a slightly scaly tan macule on photodamaged skin. Clinically, it may be difficult to differentiate from a lentigo senilis, pigmented actinic keratosis, or a flat and pigmented seborrheic keratosis. We have studied 19 cases of large cell acanthoma. Large cell acanthomas were identified histologically as having epidermal keratinocytes with nuclei roughlytwice the size of adjacent epidermal or adnexal keratinocytes, and as havingminimal nuclear pleomorphism. Histologic findings were compared with actinic keratosis and lentigo senilis. Melanocyte density and cellular proliferation were compared using HMB-45 staining of melanocytes and proliferating cell nuclearantigen (PCNA) staining of epidermal keratinocytes. Lentigo senilis and large cell acanthoma both showed increased numbers of melanocytes, as identified byHMB-45 staining. Actinic keratosis shows a statistically increased proliferation rate, as identified by PCNA staining. On the basis of clinical, histologic, and immunohistochemical staining similarities, we believe that large cell acanthoma should be considered as a reaction pattern, possibly related to lentigo senilis.

Large-cell acanthoma is a distinctive condition. Am J Dermatopathol. 1992 Apr;14(2):140-7; discussion 148.
We have studied the clinical and histopathologic features of 44 biopsy specimens of large-cell acanthoma (LCA) from 35 patients. There were 19 women and 16 men, 34-88 years of age (mean 75). The lesions were mainly located on the head and extremities, usually solitary, less than or equal to 10 mm in diameter, and of greater than or equal to 1 year's duration. However, there were also cases ofmultiple and larger lesions, and those of shorter duration. The most frequently offered clinical diagnoses were seborrheic keratosis, Bowen's disease, and LCA;two cases had the clinical features of stucco keratosis. Histologically, 41 ofthe specimens could be classified into three patterns: 16 lesions showed a basic pattern (mild to moderate acanthosis, hyperkeratosis, large cytoplasms and nuclei, hyperpigmentation, and bulbous rete ridges); 12 specimens showed averrucous pattern (papillomatosis and hyperkeratosis resembling church spires);and 13 lesions exhibited a flat-hyperkeratotic pattern (compact hyperkeratosis arranged in horizontal layers of corneocytes lying on a band-like acanthotic stratum malpighii that lacks both rete ridges and papillae). Some cases exhibiting this latter pattern showed focal bowenoid changes. Some mixed and intermediate lesions demonstrated the existence of a spectrum. We have concluded that LCA is a distinctive condition with various stages of development and is probably related to stucco keratosis. It can clearly be separated histologically from solar lentigo and from solar keratosis. As other epidermal tumors, LCA can sometimes exhibit features of Bowen's disease.