Cutaneous malignant fibrous histiocytoma (undifferentiated pleomorphic sarcoma) arising in a chronic scalp ulcer of a patient with non-bullous congenital ichthyosiform erythroderma

Scalp ulcers - differential diagnoses that should be sought!

BACKGROUND

Ulceration of the scalp is an uncommon clinical presentation, and it may be caused by myriads of cutaneous etiologies such as infections, inflammatory disorders, and malignancies. We sought to reveal the underlying etiology of scalp ulcers referred to our tertiary wound healing clinic; we would also like to propose a classification for scalp ulcerations.

METHODS

A retrospective study was conducted in an academic tertiary wound healing clinic between January 2015 and June 2018. The study was approved by the Women's College Hospital Institutional Research Ethics Board. We have also conducted a review of the literature to recognize the major causes of scalp ulceration reported in the literature.

RESULTS

We have identified a total number of 15 patients with scalp ulceration. Twelve patients with atypical scalp ulcers underwent a skin biopsy. A malignancy rate of 73% (11/15) was diagnosed histologically. The review of the literature showed 237 articles. After screening the title and the abstracts, we have selected 41 case reports for the full text review.

CONCLUSION

Scalp ulcers are uncommon but important. Our sample study indicates the high frequency of malignant etiologies presenting as scalp ulcers. These results emphasize not only the need for clinicians to be on the watch for the possibility of this option but rather highlights the need for early biopsy to prevent further complications. We hope that our paper helps to shed some light on this topic and guide clinicians on how to approach scalp ulceration.

[Atypical histiocytoma in a child]

BACKGROUND

Histiocytoma (HC) is a very common benign tumour generally seen in the lower limbs of adults, particularly women. There are, however, atypical forms of HC that behave like locally aggressive tumours, occasionally with relapse or even metastasis. Herein we report a case of locally aggressive HC in a child, which, on account of its clinical extension, required seven surgical procedures to achieve complete excision.

PATIENTS AND METHODS

A 13-year-old child consulted for a hard purplish papule measuring 8 mm in diameter located in the right lumbar region. Punch biopsy revealed a poorly delineated dermal-hypodermic tumour comprising randomly distributed moderately pleomorphic fusiform cells, arranged in bands or with storiform architecture, certain of which were multi-nucleated. The mitotic index was high (11 mitoses in 10 fields at high magnification). There was no expression by the tumour of melanocytic markers (PS100, Melan-A), histiocytic markers (CD68) or CD34. FISH analysis showed the absence of COL1A1-PDGFB fusion gene. Based on these immunohistochemical and molecular findings, a diagnosis was made of atypical HC with high cellular density. Since the lower margins of the section showed tumoural foci, surgical excision was performed with 5-mm margins. Because the lateral and vertical limits were reached in all cases, a series of five further procedures (the last of was preceded by multiple peripheral biopsies) was necessary to achieve complete excision. These multiple excision procedures resulted in total excision of 25 cm across the longest side. No clinical relapse was seen after 25 months.

DISCUSSION

Cellular or atypical forms of HC carry a high likelihood of post-surgical relapse. They are characterised by marked pleomorphism and high cellular density. In our patient, the extent of the lesion had been greatly underestimated initially, resulting in the need for several surgical procedures in order to achieve complete excision. It is thus important to highlight the predictive factors for this type of tumour in order to enable sufficiently extensive excision, or excision guided by previous biopsies, to be contemplated from the outset. These predictive factors are: young patient age, unusual location (trunk, face, neck), high cellularity, marked mitotic activity and deep extension.