|THROUGH THE LENS
|Year : 2014 | Volume
| Issue : 6 | Page : 130-131
Classic porokeratosis of Mibelli
Nidhi Singh1, Laxmisha Chandrashekar1, Nava Kumar1, Rakhee Kar2, Devinder Mohan Thappa1
1 Department of Dermatology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry - 605 006, India
2 Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry - 605 006, India
|Date of Web Publication||5-Dec-2014|
Dr. Laxmisha Chandrashekar
Department of Dermatology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry - 605 006
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Singh N, Chandrashekar L, Kumar N, Kar R, Thappa DM. Classic porokeratosis of Mibelli. Indian Dermatol Online J 2014;5, Suppl S2:130-1
|How to cite this URL:|
Singh N, Chandrashekar L, Kumar N, Kar R, Thappa DM. Classic porokeratosis of Mibelli. Indian Dermatol Online J [serial online] 2014 [cited 2019 Oct 21];5, Suppl S2:130-1. Available from: http://www.idoj.in/text.asp?2014/5/6/130/146193
A 47-year-old homemaker presented with recurrent ulcer over left palm and mildly painful fingertip swelling over left thumb and middle finger for past 1 year. She had noticed ring like skin lesion over her left palm since childhood. There was no family history of similar skin lesion. On examination, multiple annular plaques with central atrophy and keratotic ridge at the margin were seen over left side of face, lips, neck, upper back, abdomen, left forearm and left palm. Over the palm, the keratotic ridge ran over thenar and hypothenar eminence, base of fingers, first finger web space and along the thumb and middle finger causing constriction band with bulbous swelling distally at finger tips [Figure 1]; and nails of the two fingers were dystrophic at the sites adjoining the ridges [Figure 2]a-c. Annular plaque with keratotic ridge was seen over the left eyelid margins, left side of lower lip involving the mucosal surfaces of lip and lower eyelid and right side buccal mucosa. However, she did not have any discomfort in the oral cavity or eye. There was fissuring at the site of ridge over thenar eminence of left palm [Figure 1]. On dermoscopy, the ridge of the annular plaques was prominently seen along with a thin groove in the keratotic ridge [Figure 2]d. Radiography of the affected hand revealed distal digital narrowing in the left thumb [Figure 2]e. Histopathology from the ridge showed keratin-filled epidermal invaginations [Figure 3]. There was no evidence of malignancy from the biopsy taken from the fissure or the bulbous projection. Patient was started on acitretin and planned for CO 2 laser ablation of the lesions.
|Figure 1: Plaque with central atrophy and threadlike keratotic ridge at the margin over the palm, first finger web space, along the thumb and middle finger causing constriction band with bulbous swelling distally at finger tips|
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|Figure 2: (a and b) dystrophic nails of the thumb and middle finger with adjoining keratotic ridges, (c) keratotic ridge at adjoining sites of thumb and index fi nger, (d) its dermoscopic image showing the groove in the keratotic ridge and (e) radiographic image showing distal digital narrowing of the left thumb|
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|Figure 3: Keratin-filled epidermal invagination with rising parakeratotic column (H and E ×40) and inset showing higher magnification of keratin filled epidermal invaginations with irregularly arranged keratinocytes with pyknotic nuclei (H and E ×200)|
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| Discussion|| |
Porokeratosis (PK) represents a group of disorders of epidermal keratinization characterized by annular lesions with keratotic ridge, which corresponds to cornoid lamella on histopathology. 
PK was first described and named so by Mibelli in 1893, but still the etiology of PK is unclear. It is common in Caucasians particularly Italians and is rarely observed in dark skinned individuals.  The keratotic ridge represents a focal expanding clone of abnormal keratinocytes which could be due to defect in keratinocyte maturation (probably defect in terminal differentiation) or in epidermopoiesis.  It has been found to have an autosomal dominant inheritance with variable penetrance. Somatic mutations may explain the sporadic occurrence of cases of PK. In addition, various triggers such as immunosuppression, infection, drugs, ultraviolet radiation and mechanical trauma have been incriminated. The clinical variants of PK includes porokeratosis of Mibelli (PM, disseminated superficial porokeratosis, disseminated superficial actinic porokeratosis, porokeratosis palmaris et plantaris (PPP) and PPP disseminata. Nail dystrophy in PK even though rare has been noticed in cases where the lesions involve either the nail matrix or nail bed sometimes finally resulting in complete destruction of nail.  Distal digital narrowing associated with nail dystrophy has been reported in a case of linear PK.  Malignant transformation has been described in all forms of PK but the risk is highest with linear PK and giant PK.  Hence, regular monitoring for malignant transformation should be done, more so if any non-healing erosion or ulcer is seen in porokeratotic lesion.  Dermoscopy helps in better visualization of the keratotic ridge, the classic clinical morphology of PK and should be used as rapid non-invasive simple clinical diagnostic technique.  This case is being presented for the classic morphology of porokeratosis of Mibelli with nail and mucosal involvement.
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[Figure 1], [Figure 2], [Figure 3]