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[High-dose multimodal radiotherapy of confluent destructively growing aggregated keratoacanthoma. 2 case reports].

BACKGROUND
Keratoacanthoma is a fairly common, benign, usually self-resolving skin lesion that arises from the hair follicle. This nodular lesion shows a predilection for areas exposed to light, mainly for the face. We report on the intensive radiation therapy of 2 cases of a rare subset of keratoacanthoma which showed a locally aggressive, seriously destructive growth.


PATIENTS AND METHODS
Two female patients with previously treated, confluent-destructive growing keratoacanthoma were treated by multimodal, high-dose radiotherapy. Patient 1 showed a rapid progress of midfacial tumor with destructive infiltration of the left cheek, nasal cartilage, the cribriform plate of ethmoid and congestion of the conjunctiva close to the lacrimal caruncle. This could be shown in clinical and histopathological investigations and CT-scans. The coexistence of cutaneous and conjunctival lesions in locally rapidly enlarging keratoacanthoma of the face is unusual and unreported to our knowledge. One case of simultaneous conjunctival and multiple, eruptive keratoacanthoma of the body has been reported. Patient 2 had received soft X-ray pretreatment because of a large, relapsing keratoacanthoma of the left cheek.


RESULTS
Patient 1 underwent a parallel, intensive treatment of the conjunctiva with 90Sr-contact therapy, percutaneous high-dose 60Co-gamma- and megavoltage electron treatment (10 and 18 MeV) of the midfacial lesions. Conjunctiva and caruncle showed a complete remission of keratoacanthoma. In the other facial areas no long-term regression could be reached, despite giving a fully cancericidal, total dose of more than 100 Gy in some regions. Patient 2: Further high dose radiotherapy using megavoltage electron treatment with a total dose of 50 Gy showed a complete remission of the lesion for 5 months. Another relapse of this keratoacanthoma could be operated successfully. There was no more relapse established in follow-up checks.


CONCLUSIONS
The 2 case reports show that in treatment of locally destructive growing subsets of keratoacanthoma a sufficient therapy should be initiated in time. Keratoacanthoma and subsets of this lesion that do not respond well to initial treatment, recur early or show seriously aggressive growth should be treated early by combined therapy that takes previous experiences into consideration.