Matrical Carcinoma With Melanocytic Proliferation and Prominent Squamoid Whorls

Abstract

Matrical carcinoma (pilomatrix carcinoma) is a rare follicular low-grade malignancy with matrical differentiation. A pigmented variant with admixed dendritic melanocytes is exceedingly rare with only 7 cases reported in the literature. The diagnosis of malignancy can be difficult to establish. The authors report a case of a 79-year-old woman with a matrical carcinoma who presented with an ulcerated nodule on the posterior right leg, measuring 2.2 cm in greatest dimension. The excisional biopsy showed irregularly shaped dermal and subcutaneous nodules ranging in size from 0.1 to 0.5 cm. The nodules were composed of aggregates of large atypical basaloid cells, with multiple, sometimes atypical, mitoses, admixed with ghost cells, and central necrosis en masse. In addition, the neoplasm was characterized by focal marked melanocytic proliferation and multiple whorls of pink eosinophilic material reminiscent of keratin pearls (squamoid whorls). The basaloid cells were positive for beta-catenin both in the nuclei and the cytoplasm and negative for BerEp4. S100, Melan-A, and HMB45 highlighted the melanocytic dendritic cells. Pan-cytokeratin was negative in the ghost cells and focally positive in the squamoid whorls. Squamoid whorls seem to be a significant feature of matrical carcinoma.

Matrical carcinoma with melanocytic hyperplasia mimicking nodular melanoma in an elderly Mexican male

“…Previously regarded as low‐grade, the frequent recurrence after excision (23% of wide local excisions, 83% of simple) and a 13% rate of metastasis bring observations of clinical behavior in line with its high‐grade histomorphology . While melanocytes are a component of normal hair matrix, coincident melanocyte proliferation is exceptionally rare in malignant matrical neoplasms …”

“…MCMH, also known as “malignant melanocytic matricoma,” “matrical carcinoma with melanocytic proliferation,” “pigmented malignant pilomatrixoma,” “melanocytic pilomatrix carcinoma,” and “pilomatrix carcinoma with intralesional melanocytes” is a subtype of a rare tumor of the hair follicle with matrical differentiation . Previously regarded as low‐grade, the frequent recurrence after excision (23% of wide local excisions, 83% of simple) and a 13% rate of metastasis bring observations of clinical behavior in line with its high‐grade histomorphology .…”

“…This case marks the 12th instance of MCMH reported in the literature. Clinical and histopathological features of all cases to date are summarized in Table …”

Preference for the term pilomatrical carcinoma with melanocytic hyperplasia

“…Between 2003 and at the time of this writing, there have been only 7 definite reports of pilomatrical carcinoma with melanocytic hyperplasia (categorized most commonly as malignant melanocytic matricoma), including the discussion that follows. [5][6][7][8] Here, we report the case of an 84-year-old woman with pertinent past medical history of peripheral vascular disease, venous insufficiency, atrial fibrillation and breast cancer who presented to urgent care with concern for increasing inflammation in the area of a longstanding brown lesion. On examination of the posterior right lower leg, the patient was noted to have a large black plaque with a mildly erythematous surrounding ring.…”

Pilomatrical carcinoma – a case report and review of the literature

“…Pilomatrical carcinoma (PC) is a very rare low-grade cutaneous malignancy with matrical differentiation, considered to be the malignant counterpart of pilomatrixoma. It was first described in 1980 by Lopansri and Mihm [1] and until now, about 140 cases have been published in the English literature [2]. Given the rarity of this neoplasm, there is impossible to estimate its incidence, and knowledge on etiology, pathogenesis and biological behaviour is only sparse.…”