A Different Keloid in More Ways than One.

A 29-year-old female visited this clinic for a potato-shaped structure gradually growing over a linear keloid on the right upper arm that had developed over a stab injury 16 years ago. The nodular mass had started growing about 4 years ago. On examination, there was a firm linear keloid on the skin over the deltoid with a potato-shaped nodular mass with variable pigmentation growing from its proximal end [Figure 1a]. Recent pain and tenderness were reported. Personal and family history of keloids was absent. The nodular lesion was excised due to pain and tenderness. Hematoxylin and eosin-stained sections showed a thinned-out epidermis with flattened rete ridges [Figure 1b]. The mid- and reticular dermis showed deposition of bundles of hyalinized eosinophilic collagen with few intervening thin-walled capillaries and scattered fibroblasts [Figure 2a]. Overall hypocellularity was significant. Additional Mason trichrome stain highlighted the collagen by its blue color [Figure 2b]. The findings were consistent with the diagnosis of an established keloid. Intralesional triamcinolone 20 mg/ml injections are being given at the periphery of the excised lesion to prevent recurrence and the wound has healed satisfactorily with no early signs of regrowth noted after two months. A six-weekly follow up has been advised.

Figure 1

(a) Potato-shaped Keloid occurring at the proximal end of a long-standing linear keloid. (b) H and 100x: Epidermis with flattened rete ridges, upper and lower dermis replaced by dense, amorphous material.

Figure 2

(a) H and E ×400- Shows hyalinized collagen with intervening thin-walled capillaries and scattered fibroblasts. (b) Masson's Trichrome 100×- Confirming the homogenous blue staining material to be collagen.

Keloids are benign fibroproliferative skin tumors.[1] Owing to their propensity to spread beyond the margin of the original wound, gradual growth, common recurrence following excision, and rare spontaneous regression, they have been viewed as quasi-neoplastic tumors.[12] They have been divided into superficial spreading/flat keloids and raised/bulging ones.[3] They have been described as “regular” with a round shape and clear curving lines, and “irregular” with irregular shapes and lines.[4] They have also been described as (i) geometric (ovoid, linear, spheroidal and globular), (ii) recognizable (butterfly, dumbbell, propeller, petalloid, botryoid, and reniform) and (iii) irregular (nongeometrical and unrecognizable outlines).[5] They can be firm to very hard. Site-specific interkeloidal as well as intrakeloidal heterogenieity is known.[3] Deltoid, presternum, anterior chest, upper back, and earlobe are favored locations for keloid formation.[5] Keloids as seen in this case, are commonly described over earlobes. Most keloid scars on the deltoid are oriented along the anatomical axis of the upper extremity. Unusually, propellor-shaped keloids are seen where the initial lesion originates from a vaccination site with proximal and distal extensions like two blades of a propellor. Varying number of blades of the propellor and butterfly shape are also described. Dumbell, butterfly, and crab's claw-shaped keloids over scapula, chest, and shoulder are thought to be determined predominantly by local mechanical factors like stretching.[36] We attribute the transformation of the proximal part of a long-standing linear keloid into such a nodular hard tumour to the same phenomena due to its proximity to the shoulder joint which is constantly in motion.[36]

Keloids are rarely biopsied. However, accuracy of its clinical diagnosis has been reported to be 81% which may prompt clinicians to reconfirm the diagnosis by biopsy as we did.[7] Dermatofibrosarcoma protuberans, sclerosing fibroma, and keloidal dermatofibroma were ruled out histologically.[89] A need for immunohistochemical studies was not felt owing to the abundant hyalinized collagen with hypocellularity.

In conclusion, we describe a rare presentation of a keloid over the deltoid that can cause clinical confusion.

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Conflicts of interest

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