We report a case of aggressive pilomatrixoma with two recurrences. This is the first reported case of such a tumor with a basal cell-like histology of recurrences. We propose that this type of tumor be designated "calcifying epitheliocarcinoma of Malherbe" or "pilomatrixoma carcinoma."Cancer 45:2368-2373, 1980.ILOMATRIXOMA was first described in 1880 by P Malherbe as a benign calcifying tumor believed to arise from the sebaceous gland. It was not until 1961 when Forbis and Helwig reviewed 228 such tumors that the name "pilomatrixoma" was proposed.Evidence by both light and electron microscopic observation and histochemical studies favors the hair matrix as the site of origin. This tumor usually appears as a slow-growing dermal or subcutaneous mass less than 3 cm in size, most commonly located on the head or neck. It is frequently a tumor of the younger age-group with a peak incidence between eight and 13 years. More than 60% of the tumors appear before the third decade. The female to male ratio is nearly 3:2. Familial occurrence has been reported in 7 cases of pilomatrixoma." Gardner's syndrome and myotonic muscular dystrophy have been associated with cases of pilomatrixoma. Those occurring in patients with myotonic dystrophy are often multiple and are commonly familiaL2 Multiple tumors occur in 2-3 S%.ll*ls Recurrences after tumor removal are rare. In the re- view by Forbis and Helwig, 6 patients were described as having recurrences, occurring after periods ranging from one month to six years. Details of the clinical or microscopic appearance of those cases were not discussed. In 1927, Gromiko reported a case of calcifying epithelioma with three recurrences necessitating amputation of the right arm.5 Nonetheless, a malignant counterpart of pilomatrixoma has never been designated with certainty. One tumor was called a "giant calcifying epithelioma," even though it behaved in an aggressive fashion with recurrence^.'^ Hence, we are prompted to report a case wbich we think represents pilomatrix carcinoma. Case ReportA 35-year-old white man presented with an approximate one-year history of a 1.5-cm slowly growing, asymptomatic, movable subcutaneous nodule on the back at the right suprascapular area. The tumor eventually recurred twice and was widely reexcised each time, a t 15 months and 28 months after first therapy. Each excision included the underlying fascia and the superior portion of the subadjacent muscle. The first recurrence presen'ted as three small nodules, the second as a 1-cm dermal and subcutaneous mass. Local radiotherapy was given after the second removal without evidence of clinical recurrence. The patient remains without evidence of recrudescence 40 months after primary therapy. Histpathologic FindingsThe original specimen was a 1.5-cm soft, pink-tan circumscribed dermal and subcutaneous mass containing focal areas of cheesy material. Microscopic examination showed it to be a pseudoencapsulated mass com-

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We have attempted to review virtually all forms of cutaneous and mucocutaneous melanomas. Superficial spreading, lentigo maligna and nodular melanomas have been more thoroughly investigated and documented in previous studies. Lentigo maligna melanoma appears to have a longer duration and better prognosis than SSM or NM. The overall prognosis probably correlates better with the anatomic level and thickness of invasion than with type (Clark et al. 1975, Breslow 1970, 1975). It appears that certain pitfalls exist in either method of assessing prognosis, and it is recommended that both methods be applied in evaluating a malignant melanocytic lesion when feasible. With regard to in situ melanoma or Level I melanoma, it is our experience that such lesions can achieve a 100% cure rate when completely excised. Hence, we prefer to call such lesions severely atypical melanocytic hyperplasia, and thus avoid labeling these patients with a malignant diagnosis. The most difficult histologic challenge in diagnosing a lesion of malignant melanoma is the Spitz nevus. The pathologist should never be biased by the age of the patient, for a serious mistake can arise. We have seen a case of nodular melanoma in a 13-year-old girl diagnosed as Spitz nevus only to be followed by a lymph node metastasis years later. Other examples of histologic differential diagnoses of malignant melanomas include, for example, halo nevus, soft tissue sarcoma, squamous cell carcinoma with spindle cell proliferation, Paget's disease of metastatic carcinoma, (for example, from the breast). Therefore, the approach to the diagnosis of malignant melanoma necessitates an evaluation of both clinical and pathological features. Histologic study must encompass both the pattern of growth and cellular cytologic detail for successful interpretation.