Pilomatrixoma: A Description of Two Cases Diagnosed by Fine-Needle Aspiration Javier Ortiz, M.D., Carmen Garcia Macias, M.D., Mar Abad, M.D., Teresa Flores, M.D., Jose I. Paz, M.D., and Agustin Bullbn, M.D.

The present work reports on the findings obtained by Jne-needle aspiration of two pilomatrixomas located on the upper limbs whose diagnosis was confirmed histologically. In both cases, the cytology disclosed a profiferation of smalf round basaloid cefls that were dispersed and grouped in clusters together with squa- mous cells and abundant multinucleate giant cells. The differen- tial diagnosis with other neoplasms is discussed. Diagn Cytopa- tho1 1995;12:155-157. 0 1995 Wiley-~iss, Inc.

Key Words: Pilomatrixoma; Fine-needle aspiration; Neoplasms; Squamous cells; Multinucleate giant cells

Although the histological images of pilomatrixoma (cal- cifying epithelioma of Malherbe) are quite typical and commonly reported in the medical literature, 1-3 few re- ports have addressed the cytological aspects of this type of tumor, derived from cutaneous adnexa. Accordingly, we thought it of interest to describe the findings ob- tained following fine-needle aspiration of two piloma- trixomas, especially since the cytological appearance of this type of tumor may cause problems when attempting to establish a differential diagnosis with other neo- plasms.

Case Reports Case I The patient was a 30-yr-old woman with no previous his- tory of interest who presented at our fine-needle aspiration (FNA) service with a subepidermal nodular lesion of 2 cm located on her left arm. It had been present for 1 yr and had a firm consistency.

Following FNA, a marly material was obtained. After being spread onto a slide and fixed in 96% alcohol, the material was stained by the Papanicolaou method.

Under the light microscope, abundant compact clusters were observed; these were formed of basaloid cells, with a uniform appearance, scanty cytoplasm, round hyper- chromatic nuclei, thin chromatin, and small but evident nucleoli (Fig. 1). There were also squamous cells and histiocytes together with numerous multinucleate foreign- body giant cells.

After removal of the tumor, the histological study re- vealed the typical structure of a pilomatrixoma, with the presence of basaloid cells, abrupt keratinization, and ghost cell formation; there was also a noticeable degree of in- flammatory reaction to foreign bodies (Fig. 2) .

Case 2 The patient was a 19-yr-old woman with no previous his- tory of interest who attended our Service with a firm, painful 2-cm nodular lesion located on her left elbow that had been present for 6 mo. After FNA, the material was

Received June 14, 1993. Accepted March 21, 1994. From the Department of Pathology, Clinical Hospital of Salamanca,

Salamanca, Spain. Address reprint requests to J. Ortiz, M.D., Servicio de Anatomia

Patologica, Hospital Clinic0 de Salamanca, Paseo de San Vicente, 58- 182, 37007-Salamanca, Spain.

Fig. 1. Basaloid epithelial cells, arranged in clusters or isolated, with large hyperchromatic nuclei, scanty cytoplasm, and squamous cells (Papanicolaou stain x 250).

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Fig. 2. A histologic section of pilomatrixoma containing epithelial nests consisting of dark basaloid cells and light ghost cells, surrounded by a fibrous stroma that contains multinucleate foreign body giant cells (hematoxylin and eosin, X 100).

spread onto a slide, fixed with 96% alcohol, and stained by the Papanicolaou method. Cytology of the tumor dis- closed numerous small uniform cells with very scanty cytoplasm and hyperchromatic nuclei with small but evi- dent nucleoli. The cells were both dispersed and present in the form of compact clusters of basaloid appearance. Numerous giant cells (Fig. 3) and occasional squamous cells were also observed.

Histological examination of the piece removed con- firmed a diagnosis of pilomatrixoma with images analo- gous to those obtained in case 1.

Discussion Pilomatrixoma (calcifying epitheliomas of Malherbe) comprise a group of skin tumors that are generally benign and that originate in the hair root.4 Although they are most commonly diagnosed in children and young adults, they may appear at any age, their most typical location being the head and upper limbs. In our cases, we offer the cytological findings obtained on performing FNA of two pilomatrixomas from the patients’ arms. In both cases, the cellular profile obtained (basaloid cells, giant cells, squa- mous cells) coincided with that reported by other au- thors, ‘r7 although in our cases we did not observe typical “ghost” cells, which are extremely useful in diagnosis. Similarly, it was interesting that although in the two pilomatrixomas described the cellular components were identical, there were differences as regards the arrange- ment of the cells. Thus, whereas in case 1, numerous compact clusters and few free cells were observed, in the

Fig. 3. Small cluster and numerous isolates of basaloid cells and adjacent multinucleate giant cells (Papanicolaou stain, x 100).

second case there was a predominance of disperse cells as well as compact clusters.

Concerning the differential diagnosis, pilomatrixomas should be distinguished from other entities such as basal cell carcinoma, trabecular carcinoma, or the metastasis of a small cell carcinoma, which may display a similar cytol- ogy. In these cases, both the identification of the typical elements of pilomatrixoma (giant cells, ghost cells, cal- cium) and the clinical history of the patient are of great help in achieving a correct diagnosis. *

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References 1. Lever WL, Griesemer RD. Calcifying epithelioma of Malherbe.

Arch Dermatol 1949;46:39 1-498. 2. Forves R, Helwing EB. Pilomatrixoma (calcifying epithelioma).

Arch Dermatol 1961;83:606-618. 3. Shoji A, Hamada T. Histologic variation of a pilomatrixoma. Arch

Dermatol 1983;119:793-794. 4. Hashimoto K, Nelson RG, Lever WF. Calcifying epithelioma of

Malherbe. Histochemical and electron microscopic studies. J Invest Dermatol 1966;46:391-408.

5 . Moehlenbeck FW. Pilomatrixoma (calcifying epithelioma). A statis- tical study. Arch Dermatol 1973;108:532-534.

6. Gomez Aracil V, Azua J, San Pedro C, Romero J. Fine Needle aspiration cytologic findings in four cases of pilomatrixoma (calcify- ing epithelioma of Malherbe). Acta Cytol 1990;34:842-846.

7. Unger P, Watson C, Phelps RG, Danque P, Bernard P. Fine needle aspiration cytology of pilomatrixoma (calcifying epithelioma of Mal- herbe). Report of a case. Acta Cytol 1990;34:847-850,

8. Woyke S, Olszewsky W, Eichelkraut A. Pilomatrixoma. A pitfall in the aspiration cytology of skin tumors. Acta Cytol 1982;26:189- 194.

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