Dermatofibrosarcoma protuberans presenting as an atrophic red plaque

ARTICLE

A 72-year-old woman whilst being seen for a haemangioma of the right ear, was noted to have a red atrophic plaque on her back adjacent to an old scar where "a cyst" had been removed several years earlier. She stated that the plaque had been enlarging for the past several months. Her general health was good and she has had a past history of basal cell carcinoma removed from her nose and right ear as well as having rheumatic fever as a child. The cutaneous examination revealed a 3 x 1.5 cm, atrophic irregular erythematous plaque in the midback, with a focal area of induration (Fig. 1). On palpation, the lesion was soft except for the indurated area. The rest of the physical examination revealed multiple actinic keratoses on the hands and face but was otherwise unremarkable. She had no lymphadenopathy and the results of her laboratory tests were all within normal limits.

A punch biopsy of the thickened area of the plaque was obtained, and the histopathological features are shown in Figure 2.

What is your diagnosis ?

Dermatofibrosarcoma protuberans presenting as an atrophic red plaque

The biopsy specimen from the mass on the mid-back showed an epidermis that was atrophic and under which there were spindle cells within the dermis and extending into the subcutis. This tumor consisted of spindle cells arranged in a whorled pattern around blood vessels and collagen bundles. The spindle cells infiltrated between the fat cells and extended to the lateral edges of the specimen. Significant cellular atypia was not present. There was focal lymphocytic inflammation and also some histiocytic cells and isolated giant cells present. Immunoperoxidase staining showed positive staining with CD34 within the spindle cell component, and they were negative for S100, CD68, desmin and for smooth muscle actin within the tumor.

Initially a local excision was carried out and microscopic examination of the margins appeared complete on routine hematoxylin and eosin stained sections, but the tumor extended to the full depth and margins of the specimen on CD34 staining. A subsequent wide excision down to the muscle and fascia resulted in clear margins on CD34 staining.

Comments

Dermatofibrosarcoma protuberans is an uncommon locally invasive malignant tumor that arises in the dermis and has a strong tendency to recur but very rarely metastasizes (5%) [1]. It is most frequently diagnosed during the second to fifth decades of life, but all ages can be affected [1, 2]. There is a slight male preponderance in previous studies and the tumor has been reported in all races. The aetiology is unknown, but trauma may be a predisposing factor. DFSP lesions usually present as indurated dermal plaques and/or nodules that feel firm, fibrous or rubbery to palpation and fixed to the underlying skin. The tumor usually grows slowly, ranging from a few months to many years. They may range in size from 0.5 cm to 25 cm in diameter and approximately 50% of DFSPs arise on the trunk, 35% on the extremities, and 15% on the head and neck [3]. The clinical presentation is usually an indurated plaque or protuberant nodule, but it can appear atrophic [4]. Other variants of DFSP include deep DFSP (those confined to the subcutaneous tissue), DFSP-fibrosarcoma like areas, and the Bednar tumor (melanin in the spindle cells) which represents 5% of cases [5]. It is important to be aware of the atrophic form as diagnosing DFSP at the atrophic plaque stage is difficult as it must be differentiated from atrophic scars, deep morphoea, idiopathic atrophoderma, anetoderma [6], and necrobiosis lipoidica.

The absence of symptoms often results in delayed diagnosis, erythema and pain occurring in only 15% of cases. This tumor invades both by subclinical extensions laterally through collagen bundles and deeply along connective tissue septae. It is this spread of the tumor beneath clinically normal appearing skin that makes complete excision with variable margins all the more difficult as it may extend for many centimetres beyond the superficial lesion. Metasasis is rare, approximately 5%: 1% via lymphatic spread to regional nodes; 4% via haematogeneous spread (most common being the lung followed by the brain, bone and heart) [1].

DFSP has a characteristic pattern on routine hematoxylin-eosin stained sections created by spindle-shaped, fibroblast-like cells arranged in storiform, whorled, stellate or cartwheel patterns around collagenous centres or a central vascular space. The tumor has multiple microscopic finger-like projections into the surrounding dermis and subcutis, and it may even project into muscle and periosteum. The overlying epidermis may be atrophic, ulcerated or even hyperplastic.

The differential diagnosis includes dermatofibroma, malignant fibrous histiocytoma, atypical fibroxanthoma, cutaneous metastasis, fibrosarcoma, amelanotic melanoma, keloid, leiomyosarcoma and Kaposi's sarcoma. DFSPs seem to have no polarizable collagen and CD34 is used as an immunohistochemical marker for DFSP (CD34⁺, Vimentin⁺), to differentiate it from dermatofibroma and other CD34 negative tumors. DFSP should be considered in the differential diagnosis of atrophic plaques since early recognition and treatment may improve the prognosis.

Traditional treatment consists of wide (4-5 cm margins) and deep local excision to the fascia with tissue processing and CD34 staining allowing ideal pathological interpretation. Mohs micrographic surgery is preferred by some because it allows precise margin control with microscopic extensions of the tumor detected by CD34 staining of frozen sections, and removed with the benefit of conserving the maximum amount of normal tissue [7]. This is particularly important in certain areas of the body such as the face and distal extremities where there is less free skin. Radiotherapy is gaining popularity in the management of residual tumor or when excisional surgery would result in severe cosmetic and functional loss [8]. Chemotherapy plays a limited role, mainly in metastatic disease and palliative therapy.

References

1. Rutgers EJT, Kroon BBR, Albus-Lutter CE, Gortzak E. Dermatofibrosarcoma protuberans: treatment and prognosis. Eur J Surg Oncol 1992; 18: 241-8.

2. Hobbs ER, Wheeland RG, Bailin PL, et al. Treatment of dermatofibrosarcoma protuberans with Mohs micrographic surgery. Am Surg 1998; 207: 102-7.

3. Ratner D, Thomas CO, Johnson TM, et al. Mohs microghraphic surgery for the treatment of dermatofibrosarcoma protuberans. J Am Acad Dermatol 1997; 37: 600-13.

4. Lambert WC, Abramovitis W, Gonzales-Sevra A, et al. Dermatofibrosarcoma non-protuberans: description and report of five cases of a morpheaform variant of dermatofibrosarcoma. J Surg Oncol 1985; 28: 7-11.

5. Haycox CL, Odland PB, Olbricht SM, Piepkorn M. Immunohistochemical characterization of dermatofibrosarcoma protuberans with practical applications for diagnosis and treatment. J Am Acad Dermatol 1997; 37: 438-44.

6. Martin L, Combemale P, Dupin M, et al. The atrophic variant of dermatofibrosarcoma protuberans in childhood: a report of six cases. Br J Derm 1998; 139: 719-25.

7. Gloster HM, Harris KR, Roenigk RK. A comparison between Mohs micrographic surgery and wide surgical excision for the treatment of dermatofibrosarcoma protuberans. J Am Acad Dermatol 1996; 35: 82-7.

8. Suit H, Spiro I, Mankin HJ, Efird J, Rosenberg AE. Radiation in the management of patients with dermatofibrosarcoma protuberans. J Clin Oncol 1996; 14: 2365-9.

Acknowledgements