A Rare Presentation of Dermatofibrosarcoma Protuberans of the Scalp Treated with “Slow-Mohs” Micrographic Surgery

May 2022 | Volume 21 | Issue 5 | Case Reports | 534 | Copyright © May 2022


Published online April 27, 2022

doi:10.36849/JDD.6719

Reed Fezza BS,b Parastou Shahzeidi BS,a Christopher Downing MD,a,b Armand B. Cognetta MDa,b

aFlorida State University, Tallahassee, FL
bDermatology Associates of Tallahassee, Tallahassee, FL

Abstract
Dermatofibrosarcoma protuberans (DFSP) is a rare, fibrohistiocytic tumor with intermediate malignancy.1 While these tumors are slow-growing and only metastasize in 6% of cases,2 they are often locally destructive, with relatively high local recurrence rates after initial excision. Overall annual incidence rates in the US are 0.8-4.1 per million person-years,2 though incidence among African Americans is nearly double that of Caucasians.3 DFSP is most commonly seen on the trunk (42-50%), followed by the extremities (30-42%) and, rarely, on the head and neck (10-15%).2,4 Other studies report that DFSP of the scalp accounts for under 5% of total cases.5 However, the head and neck region is reported to have the highest tendency to recur locally, roughly 50-75% of cases.4 Further, DFSP tumors on the scalp have the potential to metastases to the brain,4 thus highlighting the importance for these tumors to be correctly diagnosed and treated early on.

Partly due to its rarity and also its tendency to mimic other mainly benign lesions clinically, DFSP is often misdiagnosed, leading to years of delay in proper treatment and otherwise likely avoidable sequelae.6 We describe a rare presentation of DFSP on the scalp of a 45-year-old African American woman successfully treated with "slow-Mohs" micrographic surgery. We also discuss the most common misdiagnoses for DFSP and scenarios when this tumor should be included in the differential and subsequent work-up.

J Drugs Dermatol. 2022;21(5):534-535. doi:10.36849/JDD.6719

INTRODUCTION

Case Synopsis
A 45-year-old woman presented with a one-year history of a growing mass on the scalp. The patient believed the lesion was a benign cyst and requested removal due to its painful nature. Physical exam revealed a 10x24 mm reddish raised nodule on the right parietal scalp initially clinically suspected to be a pilar cyst (Figure 1).

The area appeared inflamed, but without signs of infection. The lesion was removed with excision margins and a tissue sample was sent for histopathological diagnosis. Excisional biopsy of the lesion revealed this to be DFSP extending to the peripheral deep margins. Histological analysis showed dermal based spindled cell proliferation.

No features of fibrosarcomatous transformation were identified. There was additional staining completed for S-100 protein, Melan-A, desmin, and CD34; all of which were negative except for CD34 which stained positive.

The patient’s medical history includes the sickle cell trait, anemia, and migraine headaches. She denied any personal or family history of skin cancers or other cancers, including DFSP. She had no scar or previous trauma history to the lesion site. The patient was further treated with "slow-Mohs" surgery involving 10 mm margins taken around the lesion down to subcutaneous fascia. Focal positivity was found in two sections following stage one and the patient was brought back for a second stage of "slow-Mohs" the next day. An additional layer

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