Giant Porokeratosis: Report of Three Cases.

Giant porokeratosis (PK) is a rare entity. Many consider it as a variant of PK of Mibelli, while others describe it as a separate variant. The diameter may range between 10 and 12 cm and the wall of hyperkeratotic ridge may be upto 1 cm. High tropical temperature and long duration of outdoor activities without adequate clothing are known influencing factors of PK. To the best of our knowledge, only five cases of solitary giant PK and a case of disseminated giant PK have been documented from India. We report three cases of giant PK for their rarity. Copyright:

Introduction

Porokeratosis (PK) is characterized clinically by one or more annular plaques with central atrophy and surrounding elevated hyperkeratotic ridges that correspond to cornoid lamellae in histopathology. Five important clinical variants are recognized: disseminated superficial PK comprising both actinic and nonactinic variants (most common), classic PK of Mibelli (second most common), linear PK, punctate PK, and PK palmaris et plantaris disseminata (thought to be a subtype of punctate PK). Other rare variants are giant PK, PK ptychotropica (verrucous lesions affecting buttocks),[1] reticulated PK,[2] pruritic papular type,[3] pigmented porokeratosis,[4] prurigo nodularis-like PK,[5] etc. We report three rare cases of giant PK.

Case History

Case 1

A 45-year-old woman, farmer by profession, presented with 20 cm × 9 cm plaque on sole [Figure 1] and lateral borders of the right leg [Figure 2]. It had distinct ridge at periphery. The lesion started on right ankle as small coin-shaped annular lesion about 15 years back which gradually spread to involve the plantar and lateral surfaces of right foot. She used to work in fields with bare feet. There was no family history of this disease. With this presentation, the patient was provisionally diagnosed to have giant PK.

Figure 1

Case 1: porokeratosis involving plantar surface of right leg

Figure 2

Case 1: porokeratosis involving right lateral foot

Case 2

A 51-year-old man, rickshaw driver by profession, presented with a 41 cm × 9 cm plaque with a distinct peripheral ridge on right lower leg. The lesion started on the dorsum of foot about 12 years ago. Gradually, it progressed upwards and involved the whole of right leg below the knee [Figure 3]. Everyday he used to work for 10hours in the sun. He was provisionally diagnosed to have giant PK.

Figure 3

Case 2: porokeratosis involving right lower leg and extending to foot

Case 3

A 58-year-old male laborer, presented with rough scaly 23 cm × 13 cm plaque on right lower back [Figure 4]. Ten years back, he noted a small annular lesion. In the first year, it spread peripherally to a 2 cm × 2 cm plaque with elevated ridge. Then, it remained static for next 7 years. In last 2 years, it started to spread suddenly. He had to work with bare upper body for 8–10 hours daily and often felt itching and burning sensation when mercury got high. He was also provisionally diagnosed to have giant PK.

Figure 4

Case 3: porokeratosis on right lower back

These three cases presented in dermatology department of a government hospital in Bankura, West Bengal, India. None of them had received any treatment before. The first two cases were completely asymptomatic while the third patient experienced itching and burning sensation under the sun. The lesions increased in summer.

The patients were investigated thoroughly. Complete blood count, erythrocytic sedimentation rate, fasting lipid profile, liver function tests, renal function tests, chest X-ray, and blood sugar tests (fasting and postprandial) were all within normal limits. HIV status was negative and they were alls immunocompetent. We also considered plaque type of lupus vulgaris, psoriasis, DLE, and intraepidermal squamous cell carcinoma in our differential diagnoses. Biopsy specimens from all patients revealed cornoid lamellae, underlying absent granular and chronic inflammatory cells in papillary dermis [Figures 5a, b, 6a, b and 7], confirming our provisional diagnosis of PK.

Figure 5

(a): Arrow showing cornoid lamella, absent granular layer with mild dermal dyskeratotic cells (hematoxylin and eosin, ×40); (b): magnified view of (a) (hematoxylin and eosin, ×400)

Figure 6

(a): Arrow showing cornoid lamella, diminished granular layer, underlying dermal inflammatory infiltrate (hematoxylin and eosin, ×40); (b): magnified view of (a) (hematoxylin and eosin, ×400)

Figure 7

Arrows showing 3 adjacent cornoid lamellae with diminished underlying granular layers and dermal inflammatory infiltrates (hematoxylin and eosin, ×40)

They were advised photoprotection, capsule isotretinoin 20 mg daily and topical halobetasol 0.05% application at night daily. However, the first two cases were lost to follow up. In the third case, we did partial excision, cryotherapy, and subsequently applied 0.05% tretinoin cream and 5% fluorouracil cream alternate nights. There were side effects like erythema, pruritus, oozing, crustation, and edema after every 3–4 weeks. Then, topical 5-fluorouracil had to be stopped temporarily and restarted after healing of the wound. After three episodes like these, the patient was lost to follow up. However, a moderate improvement could be appreciated over a span of 5 months of treatment.

Discussion

Giant PK is a rare entity.[678] Many consider it as a variant of PK of Mibelli,[9] while others describe it as a separate variant. The diameter may range between 10 and 12 cm and the wall of hyperkeratotic ridge may be upto 1 cm.[7] Interestingly the histopathology slide of case no 3 revealed three adjacent cornoid lamellae. Finding of multiple cornoid lamellae is not uncommon; may be underreported. When PK spreads by centrifugal expansion, probably it leaves its footprint behind as extra cornoid lamella.

Dermoscopy, not done in our cases, is a great tool in diagnosis. It reveals double white tracks with brownish discoloration within the furrow and a white homogeneous area at the center, corresponding to an atrophic epithelium. Red dots, globules, and lines (corresponding to enlarged capillary vessels) can be seen through the atrophic epithelium.[10] Staining of the skin surface with whiteboard marker (the furrow ink test) will accentuate the dermoscopic findings and highlight hair follicles and acrosyringia (seen as multiple open pores), some with keratotic plugs.[11] Noninvasive, high-resolution imaging techniques such as optical coherence tomography and reflectance and fluorescence confocal microscopy may identify characteristic cornoid lamella[12] or differentiate between actinic keratosis and disseminated superficial actinic porokeratosis.[13]

It is essential that a biopsy specimen be taken from the peripheral, raised, hyperkeratotic ridge to demonstrate the cornoid lamella. An incisional biopsy perpendicular to the border is preferred over punch biopsy as one may lose the coronoid lamellae during processing of the later. Reed et al. proposed a new three-step biopsy technique that allowed for proper orientation of the specimen during processing[1]: drawing a line perpendicular to the rim of the lesions,[2] then performing a punch centered at the intersection of the drawn line and coronoid lamellae,[3] then sectioning along the perpendicular line. The laboratory acquisition should mention transection, and the cut sides should be placed down when processed.[14]

PK is a premalignant condition, with reports of malignant transformation from 7.5% to 11.6%.[15] The highest risk is in linear PK followed by giant PK. Giant PK is reported with dysplasia forming cutaneous horns[1617] or squamous cell carcinoma[891516171819] that might even metastasize.[19] Hence, giant PK should be ideally treated early. There are various modalities of treatment like topical 5-fluorouracil (FU), imiquimod, oral retinoid, CO2 laser ablation, 585-nm pulsed dye laser radiation, Grenz ray radiation, Nd: YAG laser radiation, cryotherapy, dermabrasion, surgical excision, and electrodesiccation. Of these, surgical excision may be the best possible treatment while topical 5FU[2021] and cryotherapy[22] are also good options.

To the best of our knowledge, only five cases of solitary giant PK[715161723] and a unique case of disseminated giant PK[24] have been documented from India, and primary authors of four of them were from West Bengal. Geographic location or race does not play an important role in the distribution of PK. We earlier mentioned that majority of cases of PK in India were reported from West Bengal.[24] The higher incidence of PK may be attributed to the higher tropical temperature. In our patients, the other influencing factor might be their occupation, i.e., long time outdoor activities without proper clothing.

The first case report of hypertrophic PK in India,[25] rare coexistence of different morphological variants of the hypertrophic variant[26] and the first case report of disseminated giant PK as well were made by from Bankura.[24] We report these three cases of giant PK for their rarity.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.